4i8 



MUSEUM OF ANIMATED NATURE, 



[PoLYGASTniCA. 



The Actinia consists of a soft fleshy cylindrical 

 body, with a base acting as a sucker, by means of 

 which the animal adheres to rocks or pebbles, at 

 leait in many species. The opposite extremity 

 pressnti a striated disc with a central oral orifice, 

 and is surrounded by tentacles, either in a single 

 row or in several rovw, capable of beinj; contracted, 

 elon^ted, and moved in various directions ; they 

 are in fact the arms by which the animal seizes its 

 prey and drasjs it to the mouth. When wailing for 

 its "prey, some mollusk or unfortunate little crab, 

 these anns are expanded like the petals of a flower, 

 and being tinted with brilliant colours present an 

 elegant appearance. 



At the base of the Actiniae nervous fibres, it is 

 asserted, have been detected diversing from several 

 ganglia ; and certainly on the outer skm of the 

 body, which is covered by a mucous investment, 

 both longitudinal and transverse muscular fibres are 

 apparent. These fibres enable the animal to con- 

 tract with great force, and assume the fignre of a 

 rounded mass, neither tentacles nor oral disc being 

 apparent. The sensibility of these creatures is ex- 

 treme ; they contract even when a dark cloud passes 

 over the sun, and we have seen the Actinia senilis, 

 which lives in the sand, eject a quantity of water 

 from its mouth and rapidly bury itself on our ap- 

 proach ; yet so tenacious of life are these animals 

 that they may be divided with impimily, and each 

 part will become a distinct animal. When trans- 

 \ersely cut asunder, the basal portion is about two 

 months in gaining its tentacles. 



The ActiniiE are extremely voracious, and seize 

 and swallow animals with which they seem inca- 

 pable of contending; they engulf crabs and shelled 

 mollusks, and distend themselves wilh their prey, 

 which their tentacles enfold and force into the 

 mouth. The process of digestion is rapid, and the 

 shells and harder part of their victims are disgorged 

 when the fleshy parts are consumed. Notwith- 

 .standing their voracity, still the Actiniae are patient 

 of hunger, and endure long abstinence without 

 apparent inconvenience. 'I'hey may be kept for a 

 considerable length of lime in a vessel of sea-water, 

 if the wafer be daily changed ; perhaps the animal- 

 cules with which it is replete aflord some nutriment. 

 It is interesting to watch them under these circum- 

 stances. We may observe them spreading abroad 

 their richly-coloured arms, and distending them- 

 selves with the water, till the oral disc swells out 

 like a thin globule ; but on the least alarm they 

 eject the fluid, draw in their arms, and contract into 

 a firm fleshy mass, which soon again unfolds, and 

 spreads its rainbow-tinted arms in quest of prey. 



With respect to the structure of these Actiniae, 

 the external tunic consists of muscular fibres inter- 

 mingled with granular bodies, apparently of a 

 iglandular nature, everywhere distributed, excepting 

 on the base. Over this musculo-glandular tissue is 

 spread a mucous layer or epidermis, which appears 

 to be frequently thrown off and renewed. The 

 stomach consists of a plicated membranous sac with 

 a papillous surface, into which the oral orifice im- 

 mediately opens. A circular muscle surrounds the 

 latter, and a similar muscle runs round the circum- 

 ference of the disc, enabling the animal to draw the 

 outer tunic over it when it contracts, so as to shroud 

 itself entirely. The tentacles are tubular, and have 

 a distinct but minute orifice at their extremity ; 

 their interior communicates with a compartment 

 between the stomach and the exterior muscular 

 wall. This compartment is not single, but divided 

 by delicate vertical laminse into numerous sections 

 or chambers, which, however, communicate freely 

 together. This divided cavity is the aerating re- 

 ceptacle, and is filled with sea-water, taken in 

 through the tubular tentacles, and expelled when 

 the animal contracts through the same tubes. We 

 have seen Actinise in water exhausted of air, and 

 in which they have been kept too long, distend the 

 aerating chamber to such an extent as to force the 

 stomach partially through the oral aperture. In 

 these respiratory chambers are the eggs or gem- 

 mules arranged in clusters on delicate membranes. 

 It appears that these gemmules either pass through 

 minute ducts into the stomach, and so escape by the 

 mouth, or becoming attached are transmitted through 

 the tentacles ; but this point is not very definitely 

 settled. According to the Abbe Diquemare the ex- 

 pansion of the Actinia! is a more certain indication 

 of fine weather than the rise of the barometer; but 

 the animals can only be watched in summer, for, as 

 he affirms, those that we see on the rocks change their 

 abode on the approach of winter ; some abandon 

 themselves to the mercy of the waves, others creep 

 along the bottom, turning themselves inside out, 

 and making use of their tentacles as feet, till thoy 

 find a suitable spot upon which to fix, in deep water, 

 where the temperature is equable and mild. Many 

 have noticed the tenacity with which the Actiniae 

 adhere to the rock, from which it is difiicnlt to re- 

 move them uninjured : we have succeeded in ob- 

 taining numbers by cautiously insinuating a thin 



broad-bladed knife or spatula between their base 

 and the surface of attachment, without inflicting the 

 least injury. 



Fig. 3847 shows a vertical section of Actinia: 

 a n, the external tunic ; b, the base ; c, the rows of 

 tentacles ; d. the mouth ; e, the stomach ; /, longi- 

 tudinal muscles uniting at the point j; A A, the 

 egg-membranes with fine ducts opening into the 

 stomach. Fis;. 3ti48 : a, the egg-membranes, greatly 

 magnified ; b, the duct ; c, the eggs ; d, the first ap- 

 pearance of the young ; e, the same, more advanced ; 

 J\ the same, still farther advanced. 



Kig. 384'J, the distribution of nerves at the base 

 of Actinia: a, the nervous ganglions ; i, the nerves; 



c, nerves of communication between the ganglions; 



d, muscular fibres. Fig. 3S50, longitudinal muscles 

 running up to the tentacles. 



Having thus explained the general characters 

 of this section Zoantharia, so far as they are pre- 

 sented by Actinia, we may now proceed to illustrate 

 the different groups it comprises, excluding the 

 MaiireporidiB, which M. <Je Blainville includes in it, 

 and of which we have already treated. 



Fig. 3851 represents the small leathery Sea-Ane- 

 mone, .'Vctinia coriacea. This species dwells on low 

 flat sandy shores, burying itself with great prompti- 

 tude when molested. 



Fig. 3852 represents the large leathery Sea-Ane- 

 mone, Actinia senilis. This species is three inches 

 broad, with a leathery unequal envelope of an 

 orange colour: the tentacles are tinged with a 

 rose colour. Like the preceding, it takes up its 

 abode on the sand, and buries itself when alarmed. 



Fig. Sa'JS is the purple Sea-Anemone, Actinia 

 equina. The rocks and reels along our Southern 

 coast may be seen studded with this beautiful 

 species, as if with flowers of the most lovely tints. 

 The skin is soft and usually of a purple or olive 

 green, and the tentacles are of the finest violet, 

 mingled often with pink, yellow, and green ; indeed 

 the colours vary so much in different individuals, 

 all alike beautiful, that it is impossible to describe 

 them rigidly. Where the rocks along the coast 

 contain basins or little pools of clear water, during 

 the ebb of the tide these creatures may be contem- 

 plated on a fine day to great advantage, and few 

 spectacles are calculated to afford more pleasure 

 to a lover of nature. " JNIany a time and ol't " have 

 we watched tliem by the hour, and seen thera en- 

 gulf the prey which we have quietly placed within 

 the grasp of their rainbow-tinted arras. They ap- 

 peared to us to revel in the warmth of the sun, but 

 to avoid its glare, afl'ecting most the spots where 

 the rays fell subdued ; we never saw them change 

 their place voluntarily. 



Fig. 3854, the white Sea-Anemone, Actinia plu- 

 mosa. In this species, which is white, the margin 

 of the oral disc is expanded into lobes furnished with 

 numerous tentacles. It measures upwards of four 

 inches in breadth. 



Fig. 3855 shows the upper surface and base of 

 the Actinia (Discosoma) helianthes, in which the 

 tentacles are extremely short. 



There is a species of Actinia (A. Jordaica) found 

 in the Mediterranean with deep crimson tentacles, 

 which is esteemed by the Italians a great delicacy 

 for the table ; in tropical countries many species are 

 used as food. 



In the ' Ann. des Sciences Naturelles,' 1842, M. 

 de Quatrefages describes some remarkable vermi- 

 form Actiniadae under the generic title of Edwardsia. 

 These animals are invested with a sort of mem- 

 branous tube or sheath, which they coat over with 

 particles of sand and gravel, compacted by means 

 of a glutinous secretion. Three species were dis- 

 covered by M. Quatrefages on the west coast of 

 France, and a fourth was found by Professor E. 

 Forbes in the Grecian Archipelago. This species, 

 Ed.vardsia vestita. Fig. 385G, can move up and 

 down freely in its membranous tube, and an indi- 

 vidual kept for some time in sea-water, when the 

 tube was injured, came out of it altogether and 

 moved about, twisting its body like an annelide. 

 On being supplied with sand and gravel it pro- 

 ceeded to construct another covering, rolling itself 

 up in the sand, and secreting glutinous matter for 

 the membranous lining. It was very voracious, and 

 attacked whatever animal came within the reach of 

 its tentacles. 



This species lives buried in the sand, in places a 

 few inches below sea-level. 



Another remarkable genus of the Actiniada is 

 termed Iluanthus (Forbes, ' Ann. of Nat. Hist.' 

 1840) : one species only is known, viz., Iluanthus 

 Scoticus, Fig. 3857. The body is free and tapers 

 posteriorly to a point, which is most probably buried 

 in the soft mud among which it lives. The mouth 

 is surrounded by numerous long filiform tentacles. 

 This singular species was found in four fathoms of 

 water in Loch Ryan. 



A singular form of the Actiniadae is that consti- 

 tuting the genus Capnea, Forbes ; of which only 

 one species appears to be known, viz., Capnea san- 



guine]b, Fig. 3858, a native of the Irish Sea. The 

 disc is round, with several circles of exceedingly 

 short tubular and retractile tentacles ; the lower 

 part of the body is covered with a peculiar epi- 

 dermic membrane, with its upper margin turreted. 



We now turn to the family Zoanthidic, which we 

 may describe as Actiniae springing from a common 

 fleshy base or spreading root. 



Fig. 3859 represents — A, Zoanthus Solanderi, 

 from the West Indies: B, Corticifera glareola, from 

 Guadaloupe; and C, Mamellifera auriculata, from 

 the West Indies. 



Another family, containing only one genus, is 

 termed Lucernariadse. The genus Lucernaria com- 

 prises several species of beautiful campanulate 

 animals fixed to sea-weeds by a narrow disc or 

 stalk, from which they expand into a broad octa- 

 gonal surface with a lut't of tentacles at each angle, 

 and in the centre a quadrangular mouth, round 

 which are diverging festoons of egg-sacs. Inter- 

 mediate between the tufts of tentacles are little 

 coloured lobes, which some naturalists have re- 

 garded as eyes. All the species recorded are 

 natives of the British and Norwegian seas. They 

 measure about an inch in length and are usually of 

 a pink colour ; they swim with great rapidity, alter- 

 nately dilating and contracting their bodies, but 

 are usually to be seen adhering to fronds of sea- 

 weed ; they feed on small Crustacea, which they 

 seize while passing near, and which, if they really 

 possess organs of vision, they perceive when ap- 

 proaching. Fig. 3860 represents the Lucernaria 

 auricula. It does not appear quite certain that 

 these animals belong to the same section as Ac- 

 tinia ; they appear indeed to approach the Medusae, 

 and may perhaps be an intermediate link. 



CLASS POLYGASTRICA. 



There are two very distinct classes of animalcules, the 

 Rotifera and Polygastrica, which the older natural- 

 ists confounded under the general term Infusoria, be- 

 cause it was principally in vegetable infusions that 

 these atoms of creations were observed. But since 

 the improvements of the microscope, diligent 

 research has led to a better acquaintance with the 

 structure of these beings, and enabled the natural- 

 ist to ascertain their distinguishing characters. 

 The Polygastrica, or many-stomached animalcules, 

 abound in the sea and in fresh waters, every cubic 

 inch of which often teems with myriads. Some spe- 

 cies however are far more common than others, and 

 the water of every ditch, and every drop of vegilable 

 infusion exposed for a few daj's to the sun and air, 

 swarm with them. These animalcules appear to be 

 divisable into two groups : one distinguished by the 

 soft or shell-less condition of the body ; the other by 

 the body being more or less protected by an extremely 

 fine and transparent shell, varying greatly in form in 

 various species. The shelled Polygastrica are and 

 have been among the agents by which the condition 

 ' ofthe surface ofour globe undergoes change. Rocks 

 j and extensive strata are replete with their exuviae; 

 I as the countless myriads die through a long suc- 

 I cession of ages, the accumulation of their hard 

 I investments mixed with calcareous or silicious 

 matter becomes consolidated into clay, flint, chalk, 

 &c. The Turkish stone used for making hones is a 

 mass of the fossil relics of microscopic animalcules. 

 In Sweden on the shores of a lake near Urnea is a 

 va.st quantity of extremely fine pulverulent mat- 

 ter, resembling flour. It is called mountain meal 

 by the natives, and is used as food, being mixed 

 with flour. This mountain meal, which is apparently 

 somewhat nutritive, consists of nothing else than the 

 shelly coverings of certain polygastric animalcules, 

 which as the animals perish accumulate from age to 

 age at the bottom of the water and form a deep 

 stratum, and this, as the water dries or retires from 

 parts formerly covered, assumes the mealy appear- 

 ance whence it has its name. 



Some of the Polygastrica present wonderful 

 changes of form, and seem as if they had no defi- 

 nite or settled configuration. Their actions lead to 

 the inference that they are endowed with instinct. 

 They know how to pui-sue their food, what to take 

 and what to reject, and how to avoid danger. They 

 swim about with great activity, and though thou- 

 sands tenant a single drop of water, they steer clear 

 of each other in their mazy dance, or pursue each 

 other, the larger endeavouring to make the smaller 

 their prey. The minutest of these animalcules 

 which the finest microscopes have brought within 

 our vision, are termed monads ; thev appear in 

 the form of mere points or globules. Some idea of 

 their minuteness may be formed when we state that 

 five hundred millions move about freely and disport 

 in a single drop of water. With respect to their 

 organs of locomotion, some make for themselves at 

 will arms or paddles by shooting forth portions of 

 their body; others are furnished with vibratile 

 cilia, or jointed bristle-Uke appendages ; but in some 

 no especial organs of locomotion can be discerned. 

 According to Ehrenberg and others, the digestive 



