406 



MUSEUM OF ANIMATED NATURE. 



[ROTIFERA. 



carbonate of lime deposited to rorm these spines as- 

 sumes a semi(ir)stalline striu-ture, its particles obey- 

 ing the laws of chvmical affinity. Accuitling to some 

 the cleavage of these spines presents the rhomboidal 

 angles characteristic of carbonate of lime. 



The Echinus subsiists chiefly on young shell-fi»h, 

 crabs, &c., and is provided with a very curious 

 dental apparatus, surrounded by fimbriated lips and 

 long tentacles. The plates around the mouth are 

 small and less immoveably compacted together 

 than those of the other parts, and admit of being 

 altered in position by the movements of the teeth 

 and oral mart^in. From the oral orifice the points 

 of five thiee-sidcd prismatic teeth protrude exter- 

 nally and converge together, so as to act on prey 

 by the working of muscles upon the osseous jaws 

 in which they are imbedded. The jaws are five in 

 number, and each jaw examined separately resembles 

 a triangular pyramid ; when in their natural situa- 

 tion they form a five-sided cone. The teeth they 

 support have the points extremely hard, yet, as in 

 the case of the incisors of a rabbit, they wear down 

 by use, and grow as they wear down, from soft and 

 fibrous roots upon a secreting pulp. Each jaw is 

 acted upon by powerful muscles, and the whole is 

 based upon a curious osseous framework of levers 

 with corresponding muscles, too complicated to be 

 understood from a mere description. 



From the mouth a narrow gullet leads to the 

 digestive lube, which coils loosely twice round the 

 inside of the shell, and terminates as the part of the 

 shell opposite to the mouth : it is supported by folds 

 of mesenteric membrane. The nutritive fluid ab- 

 sorbed from the digestive tube entere a vein which 

 runs the whole length of the alimentary canal, and 

 terminates in a vascular ring round the mouth, 

 whence arteries are given off to the different parts 

 of the system. Aiiration is effected by the absorp- 

 tion of water into the cavity of the shell through 

 minute orifices, distinct from those through which 

 the suckers are protruded. At certain periods of 

 the year five internal sacculi are found distended 

 with eggs, which, under the name of the roe of the 

 sea-egg, are in request as an article of food in the 

 South of Europe and along the Mediterranean. This 

 roe is of a reddish colour, and said to have an agree- 

 able flavour. 



In the depressed Scutellae the ambulacra and their 

 suckers are but imperfectly developed ; and the shell 

 is covered over with minute spines like fine short 

 hairs ; these, when microscopically examined, are 

 found to be of the most admirable and elaborate 

 structure ; consisting of a series of joints of several 

 facets, and furnished with most minute spikes. 

 These miniature spines are articulated to the shell 

 by a ball-and-socket joint. By the action of these 

 instruments the Scutellae bury themselves with great 

 facility. In Spatangus (Fig. 3778) the body is ova!, 

 and the ambulacra form four leaf-like impressions 

 diverging from the mouth ; the ejestive orifice is 

 terminal. The spines are short, flat, sessile, and 

 scattered. In the figure these spines are wanting. 

 The shell is delicate. Fossil Echinida^ abound in 

 various strata from the transition beds upwards ; in 

 the chalk they are extremely common. We have 

 before us several perfect specimens from Gravesend. 



Let us now turn to tne Holothuridae and Fis- 

 tularidee. 



Fig. 3780 represents — 1, Holothuria Phantapus ; 

 I a, appendages round its mouth; 2, Holothuria 

 papillosa; 2 a, a branch of its oral appendages 

 isolated ; 3, Holothuria vittata ; 4, Holothuria cu- 

 cumis; 5, Holothuria tubulosa; 5 a, its oral ex- 

 tremity ; 5 b, its terminal extremity ; 5 c, some 

 of the cirrhi which cover the body, of the natural 

 size. 



In the Holothuridae there is no calcareous box, 

 but the body is invested in a dense fibrous skin of 

 considerable thickness, covered externally with a 

 thin epidermis, lubricated by mucus ; internally 

 there is a subcutaneous tissue of a semicartilaginous 

 structure, with tendinous fibres crossing in various 

 directions, serving to retain the shape of the body, 

 which recovers itself when bent or distended. The 

 form varies, but is in general more or less elongated, 

 whence the common appellation of sea-cucumbers. 

 Most of these animals inhabit the warmer seas, 

 and in China certain species are accounted de- 

 licacies. 



These animals, though wanting plates and spines, 

 are still furnished with retractile suckers or feet, 

 diversely arranged in different species. In H. 

 Phantapus, of the European Seas, the feet are dis- 

 posed in three rows along a sort of disc on the 

 ventral surface. When the animal creeps along, it 

 raises the two extremities of the body. In H. pa- 

 pillosa the body is covered with retractile papillic 

 or suckers. In H. tubulosa the ventral surface 

 alone is covered with papillae. In the vermiform 

 H. vittata the papilla; are small and scattered. In 

 H. cucumis there are five double rows of these 

 suckers running longitudinally, and the body is 

 pentagonal. 



^ Besides the skin and fibro-cartilaginous tissue, 

 ' there is within a pannicle of strong muscular fibres 

 I forming bands, which pass obliquely, longitudinally, 

 I and in a circular direction, the movements of the 

 , animal being thus amply provided for. 



This muscular pannicle is lined with a peritoneal 

 membrane, of which reflected ribands support the 

 viscera. The contractile power of this muscular 

 tunic is very great, and its irritability extreme, 

 inasmuch that the slightest stimulus causes violent 

 and uncontrollable contractions. Thus it mostly 

 happens when one of these animals is captured, 

 that it is thrown into such an inordinate state of 

 spasmodic rigidity, as to lacerate the viscera and 

 produce death. 



The mouth is a simple contractile orifice, sup- 

 ported by very fragile calcareous jiieccs, of no use 

 as teeth, but serving for the attachment of muscular 

 fibres ; it is surrounded by tentacula, or fringed 

 appendages, varying in different species, and which 

 are organs of touch and prehension. They are 

 capable of being protruded and withdrawn inter- 

 nally. The alimentary canal is extremely long, but 

 simple, and" its length may be the more requisite 

 from the circumstance that the Holothuria swallows 

 sand, the d(;biis of corals, portions of sea-weed, &c., 

 from which the nutritive matter, of inconsiderable 

 quantity in proportion, has to be extracted. 



The respiratory organs of the Holothurida; are 

 very beautiful : they consist of two long tubes, rising 

 from a cloacal sacculus, and giving off branches 

 dividing and subdividing into the most delicate 

 arborescent ramifications, till their minuteness be- 

 comes extreme. One of these arborescent branchia) 

 is spread over the viscera, the other is attached 

 to the inner surface of the peritoneal lining of the 

 muscular tunic. Through these tubes is the water 

 forced by the contraction of the sacculus from 

 which they spring, and in their extreme ramifica- 

 tions the aeration of the circulating fluid is effected. 



Long and numerous ovigerous tubes open by a 

 common canal in the neighbourhood of the mouth. 

 The circulatory and nervous systems are not defi- 

 nitely understood. It would appear that in all there 

 are salivary follicles. 



In the Moluccas, the Pineapple Holothuria (H. 

 Ananas), nearly two feet long, is in high request as 

 food ; indeed a great Oriental traffic in Holothuria; 

 is carried on, fleets of Malay proas visiting the 

 islands north of Australia, the coast of New Holland, 

 Timor, New Guinea, Ceylon, &c. from Macassar, 

 for the fishery of the Trepang, or Tripang, as these 

 animals are termed. On the return of the fleet 

 to Macassar the fishermen are met by the Chinese 

 tradere, who purchase the cargoes of the vessels. 

 The animals are procured by diving. They are 

 split, dried in the sun, and smoked over a wood 

 fire. In the market of Macassar not less then thirty 

 varieties are distinguished. They are then packed 

 into piculs, each picul being one hundred and 

 thirty-three pounds and a half, and about one hun- 

 dred piculs form the cargo of a single proa, averag- 

 ing from forty to fifty dollars a picul. The black 

 sorts, called " baatoo," are in most request ; the 

 gray or white, called "koro," are in less esteem, 

 the picul being not worth more than twenty dollars. 

 Besides Tripang, these vessels trade in shark-fins, 

 and the edible nests of certain species of swallows. 

 The quantity of Tripang annually sent to China 

 from Macassar is about seven thousand piculs, or 

 eight thousand three hundred and thirty-three 

 hundredweight. Crawford says it varies in price 

 from eight dollars to one hundred and fifteen dollars 

 the picul, according to quality. We learn from M. 

 delle Chiage that the poorer inhabitants of the 

 Neapolitan coast eat the Holothuiiae of the Medi- 

 terranean. 



We may now turn to the Fistularidae, which in 

 many points closely approximate to the Annelida;. 

 They have a worm-like body, and are entirely 

 destitute of suckers. They bury themselves in 

 holes in the sand in shallow parts of the sea, and 

 from these retreats protrude the head for the pur- 

 pose of procuring food, or for respiration and the 

 enjoyment of warmth ; but they seldom emerge 

 entirelj*. One species, Siponculus edulis, is in 

 esteem among the Chinese of Java as an article of 

 food ; and a species found on the sandy coasts of 

 Europe, Thalassema echiurus, is used as a bait by 

 fishermen. The skin, with its muscular pannicle, is 

 much the same as in Holothuria, and the oral orifice 

 is surrounded by tentacles, which are highly sen- 

 sitive, and are organs for the acquisition of food. 

 The alimentary canal is long and simple, but greatly 

 convoluted, and forming two loops, terminates at 

 the upper third of the body. There is a distinct 

 venous and arterial system ; and nervous ganglia 

 upon the oesophagus, whence radiate nervous fila- 

 ments to different parts of the body, may be readily 

 detected. 



Among the principal genera of this family, " Les 

 Echinodermes sans pieds " of Cuvier, may be enu- 

 merated Molpadia, Minyas, Lithoderma, Siponculus, 



&c. Cuvier also refers to the genus Bonellia, of 

 which one species, the Bonellia viridis. Fig. 3781, is 

 a native of the Mediterranean. 



In this genus the body is oval, and gives oft" a 

 long proboscis, consisting of a folded strip or 

 narrow plate ; this proboscis is capable of great 

 elongation and contraction, and divides at its ex- 

 tremity into two branches. The Bonellia viridis 

 buries itself deep in the sand, its proboscis alone 

 emerging to reach the water, or, if this be low, 

 during the ebbing of the tide, to gain the air. The 

 forked extremity of the proboscis is not rolled up 

 so as to form a complete tube, but resembles a 

 split reed ; it is moveable in all directions, and 

 doubtless serves for the seizure of food, which is 

 conveyed down the stem of the proboscis to the long 

 and highly convoluted alimentary canal. 



CLASS CfELELMINTHA (Owen). 



The class Cajlelmintha contains certain Entozoa or 

 Parasitic Worms, in which the sexes are distinct, 

 and in which nervous filaments, and sometimes even 

 nervous ganglia, can be detected. There are more- 

 over distinct muscles, and a digestive apparatus 

 enclosed in an abdominal cavity. As examples we 

 may mention the Guinea-worm (Filaria Medmensis) 

 which buries itself in the skin ; the Filaria oculi, a 

 minute species which has been found in the aque- 

 ous chamber of the eye ; the Linguatula ; and various 

 species of Ascaris. 



At Fig. 3782 we see two of these Ceelelmintha, 

 the lower specimen being evidently one of the 

 Sterelrainthous group. 



Fig. 3783 represents the Strongylus equinus: it is 

 furnished with a spherical head, and the mouth is 

 armed with soft spines. This species penetrates 

 into the arteries of the horse by some unaccountable 

 method, and in attacks of bronchitis numbers are 

 often found in the larynx and bronchial tubes of 

 that animal after death. 



CLASS ROTIFERA 



(Whkel-i.ike Animalcules). This singular class 

 of microscopic beings was formerly confounded with 

 the Polygastrica under the general title of Infusoria. 

 The Rolifera are, however, not only distinct, but 

 occupy a far higher grade in the scale of organic 

 life. They derive their name from the appearance 

 of wheels turning round and round, near Uie mouth 

 or at the upper part of the body, with great velocity. 

 This appearance is deceptive, and is found to arise 

 from circlets consisting of minute cilia, which in 

 rapid succession bend and unbend, producing the 

 effect sometimes of waves chasing each othtr in a 

 ring, at other times of wheels in rapid whirl. These 

 cilia are sometimes quiescent, sometimes only 

 partially agitated. They propel the microscopic 

 beings through the water, and moreover serve for 

 the acquisition of food. Fixing itself by means of 

 a caudal forceps to any object, the animal throws 

 its cilia into violent action, producing a whirlpool 

 in the contiguous water, conveying to its mouth 

 and hurrying thither such minute particles of animal 

 or vegetable matter as are drawn into its mimic 

 Chary bdis. When not in use the cilia are re- 

 tracted. 



The Rotifera are divided into two orders, Nuda 

 and Loricata ; the former naked, the latter covered 

 with a delicate transparent horny or calcareous 

 tunic, through which the internal viscera may be 

 seen. The mouth leads to a gullet, variable in 

 size in different species, and this conducts to a 

 gizzard or preparatory receptacle, termed by some 

 the pharynx, which is muscular and armed with 

 three curious teeth, for the purpose of comminuting 

 the food; these teeth are extremely hard, but vary 

 in size and shape in the different species. From 

 this muscular teeth-armed gizzard a canal of vari- 

 able length leads to the true stomach, to which are 

 certain appenda«;es, regarded by Professor Jones 

 as the rudiments of a biliary apparatus. These 

 appendages vary in form and number. Bands of 

 muscular fibres have been also detected, and ac- 

 cording to Ehreiiberg, even nerves and organs of 

 vision. He also considers that there exists an ex- 

 tensive vascular system. With respect to respira- 

 tion, he conceives that the water is admitted into 

 the cavity of the body through a tube at its upper 

 part, and rejected through the same, the body 

 alternately contracting and expanding, and that 

 certain little vibrating points attached to two 

 lateral undulating viscera perform the office of 

 branchiae. 



The Rotifera are oviparous, but the eggs are 

 sometimes hatched before exclusion ; they appear 

 under the microscope like minute transparent glo- 

 bules, in which the enclosed young animalcule may 

 be distinctly seen. 



The Rotifera are active and vivacious creatures, 

 and by the vigour and address of their movements 

 surprise those who observe them : to these tinv 

 creatures a drop of water is a lake, in which mill- 



