ACALKPH.!:.] 



MUSEUM OF ANIMATED NATURE. 



419 



apparatus consists of a mouth leading into a number 

 of internal sacculi, or stomac-lis, variously arrane;ed 

 ill diftereiit species; sometimes, as Monas atoraos, 

 Fi'JT. 3^61. suspended by tubes in a cluster; some- 

 times, Leucophrys patula, appended to a windiuij 

 intestinal tube. Fis:. 3862 represents Leucophrys 

 patula ; and Fig. 38G3 the alimentary canal with 

 the appended sacculi. These sacculi, or presumed 

 stomachs, are more clearly to be seen when the 

 animals have swallowed water in which indigo or 

 other vesretable colourins: matter is suspended with- 

 out beingchemically dissolved. It must be observed 

 that some zoologists differ I'rom Ehrenbeisr as to 

 the nature of these presumed stomachs. Professor 

 .Jones states that his own observations, made with a 

 very powerful microscope, did not enable him to 

 detectthc arrangement of any tube or appended sac- 

 culi ; nor was he able to peroeive, when one of the 

 carnivorous animalcules had swallowed another, that 

 the prey wis conveyed into one of these so-called 

 stomachs, but only into what seems_ a cavity ex- 

 cavated in the general paienchyma of the body. 

 He states that these pretended sacculi have no ap- 

 pearance of being attached to any tubes by means 

 of peduncles, and that so far from appearing to be 

 contiected with a central canal, as represented by 

 Ehivuberar. they are in continual circulation, moving 

 up one side of the body and down the other, and 

 even changing their relative positions like the co- 

 loured eranules visible in the gelatinous substance 

 of the Hydra. In no instance, moreover, lias he 

 been .able to detect a centra) tube, much less the 

 branches leading from it to the sacs; and he adds 

 that the circumstances attending the prehension 

 of food would in themselves lead us to imagine a 

 structure different from that described by Khren- 

 berg. He adduces, by way of confirming his views, 

 the chances of form which these animalcules under- 

 go when devouring prey nearly equal to themselves 

 in hulk, and therefore incapable of entering one of 

 these sacs. The mouth dilates to engulf the victim, 

 and when this is swallowed the whole body becomes 

 are.atly distended. It is very remarkable that in the 

 Hydra the srranules referred to, which certainly are 

 not stomachs, become tinged by the juices of the 

 prey on which the creature feeds ; these juices, by 

 some means unknown at present, are absorbed by 

 the granules, which, thus charged with nutriment, 

 circulate throngh the gelatinous substance of the 

 body. 



The reproduction of the Polygastrica is by buds, 

 by spontaneous division, and by eggs ; and some 

 species exhibit each of these modes of continuing 

 the race. Fig. 3S64 represents Bursariatruncatclla, 

 a large animalcule found in stagnant water, and 

 visible by the naked eye. It is shown magnified 

 and of the natural size. 



CLASS ACALEPH^. 



The Acalephse, or Sea-nettles (uxxXnipn, a nettle), 

 constitute a most extraordinary class of living 

 beings. They are natives exclusively of the ocean, 

 which teems with them, from the intertropics to 

 the polar circle. Among the strange and beautiful 

 of the creatures which tenant the thronged and 

 populous waters of the sea, they exhibit sometimes 

 the most fanta.stic, sometimes the most elegant 

 figures, adorned with colours of surpassing richness ; 

 nor is their variation in size less diverse than that 

 of their Ibrms. Some are so minute as to require 

 the aid of a microscope in their examination ; others 

 form large masses, which as Ihey float on the waves 

 cannot but attract attention. " Many shine with 

 phosphorescent brilliance ; as the vessel ploughs 

 the briny water, or the oars of the boat throw up 

 the spray, when d.arkness covers the face of the 

 deep, tbey glitter like a shower of stars, and falling 

 again are lost in a sea of effulgence. Some appear 

 in the depths like balls of glowing metal ; some 

 move with an undulating course, appearing as they 

 pass like a riband of flame ; others like diamonds 

 gem the rocks, or the fronds of seaweed ; some float 

 in shoals, displaying the lovely tints of the rainbow ; 

 while others, like orbs of silver, glitter as they float 

 on the rolling cuirent. 



Most are endowed with the property of stinging 

 the hand which touches them ; hence their title 

 Acalephse, or Sea-nettles (first applied to some of 

 the species by Aristotle), and the French name of 

 "Orties de Mer." The stinging or smarting sen- 

 sation which they cause, and which is often very 

 painful and accompanied with inflammation, is 

 owinsr to a peculiar acrid secretion which exudes 

 from their bodies or tentacles. 



They appear to b? of a homogeneous and gela- 

 tinous CL.n»istence, and in reality are composed of 

 filmy tissues, disposed in a cellular manner, and 

 enclo>;ing an abundance of sea-water, which when 

 they are left dead on the beach soon dries up, 

 leaving a little scum or filmy web behind. Yet 

 thfy m ivi- at will, seize, devour, and digest their 

 prey, many being even formidable to fishes. Often 

 Vol. IL 



has it surprised us to find a large Medusa thrown 

 upon the shore, reduced in a few hours, by the eva- 

 poration of the water it contained, to a trifling filmy 

 shied of only a few grains weight. 



The AcalephiB are divided into five distinct sec- 

 tions or orders, of which four derive their names 

 from their organs of locomotion; but the fifth from 

 the peculiar divided structure of the body, which 

 consists of two parts joined together by a very slen- 

 der attachment. The orders are: 1, Pulmonigrada 

 (pulnio, a lung, and gradior, to advance) ; 2, Cilio- 

 grada; 3, Physograda [(fuma,, to inflate); 4, Cirrhi- 

 grada; 5, Diphyida (A/,-, and ipv», natura). The 

 Pulmonigrada (Pulmograda, De Blainville) derive 

 their name trom the circumstances of their alternate 

 contractile and expansive movements, at regular 

 intervals, like those of the lungs in the action of 

 bre.atliing, by which movements the animals propel 

 themselves along on the surface of the water. We 

 think, however, the term very objectionable, for it 

 conveys the itiea of moving by means of lungs ; and 

 might be advantageously changed for the term 

 Discograda, as it is by the flapping of the disc that 

 these creatures swim about. 



The Pulmonigrade Acalephae, or Jelly-fish, as 

 Medusa and others, resemble in form a mushroom 

 or expanded umbrella, or the section of a globe, 

 more or less concave below. On the under surface 

 is seated the oral orifice, but in some there are cer- 

 tain pendent processes, which are destined for the 

 absorption of nutriment, and in others there is a 

 proboscidiforni appendage. 



The circumference of the disc is often furnished 

 with tentacles, which appear to be used in the 

 capture of food; indeed, fishes of some size have 

 been Ibund enfolded by them, and quite dead, killed 

 probably fiy the stinging quality with which they 

 are endowed. 



But though the species with mouths may swallow 

 fish, in the Rhizostoma, which has no mouth, such 

 prey cannot be swallowed. In this form there is a 

 thick peduncle, divided into eight foliated laminae, 

 .and terminating in as many dilated appendages. 

 The appendages and Ibliated laminae are traversed 

 by canals wilh absorbing orifices opening exter- 

 nally; and these canals ascending the peduncle, 

 ultimately merge into a single tube leading directly 

 into the stomach or digestive cavity placed in the 

 centre of the disc. It is then by the absorption of 

 fluid containing myriads of animalcules through the 

 minute apertures of the foliated puduncle, that 

 nutrition is effected. From the stomach radiate 

 canals anasioniizing and dividing, and ultiniately 

 merging into a circular tube running round near the 

 margin of the disc ; whence again arises a border 

 plexus of fine tubes like delicate network, the 

 respiratory portion of this arterio-iuitritive system. 

 A very large species, the Rhizostoma Cuvieri, is 

 abundant in our seas, and alter a storm hundreds 

 are often thrown on the shore. 



In other forms the mouth itself leads into the 

 digestive cavity, which is generally divided info four 

 compartments by an extremely delicate membrane 

 with branching tubes in various directions, and 

 marginal egestive orifices. There is also round the 

 margin a series of granular bodies, perhaps of a 

 glandular nature, which appear to communicate by 

 means of minute tubes with the nutritive canals. 

 Their use is unknown. With respect to the organs 

 of the senses, Ehrenberg and I)r. Grant consider 

 that in the Cyanea aurita organs of vision exist 

 in the form of eight small red points in depressions 

 around the margin of the disc, and Dr. Grant con- 

 siders that in some of these beings he has been able 

 to detect a nervous system. The subject is still 

 however in obscurity. The Medu.sae are certainly 

 sensitive ; they even appreciate the influence of 

 light, and when floating on the calm sea, direct 

 their own course, and avoid danger, insomuch that 

 it requires some dexterity to catch them by means 

 of a net or boat-hook, for as they near the boat they 

 gradually sink, as if alarmed by the motion of the 

 oars ; and indeed when we attempt to seize them 

 in the water, they avoid our grasp with far more 

 address than might be imagined from their ap- 

 pearance. 



The egg-sacs are radiated, and open into the 

 stomach, and besides these there is, strange to say, 

 in certain species, as in Cyanea aurita, a marsupial 

 apparatus in the Ibrm of small flask-shaped pro- 

 cesses developed on each side of the oral tentacles; 

 from the egg-sacs the eggs, in some manner not 

 fully understood, are transmitted to the pouches ; 

 here they develop, and in due time the young Me- 

 dusae make their exit in the form of ciliated ani- 

 malcules, afterwards they assume the form of an 

 eight-armed polype, and ultimately, in February or 

 March, undergo their final metamorphosis. fhe 

 marsupial pouches are deciduous, and disappear 

 soon after the escape of the young. 



It is satisfactorily proved that some of the Me- 

 diisJB, and perhaps all, are dioecious, the male and 

 female being distinct. In many seas the water is 



crowded with myriads of small luminous species ; 

 lor example, in the Red Sea, according to .Mr. Salt, 

 they teem in such profusion .as to bear a proportion 

 of one-third or even one-half to a given volume of 

 the water. We must now tuni to our Pictorial 

 specimens. Fig. 3865 represents Eudora undulosa, 

 in which, according to Pcron and Lesueur, the body 

 is greatly depressed, and without cirrhi or pe- 

 duncles ; and exhibits internally only ramified 

 canals, with four large trunks forming across: a, 

 the upper surface ; b, the same in profile ; c, the 

 under surface. With respect to several points of 

 structure in the genus Eudora further observations 

 are needed. 



Fig. 3866 represents Charybdaea periphylla. The 

 body in the genus Charybda>a is hemispherical or 

 subconical, and furnished at its circumference with 

 foliaeeous subtentacular lobes. The stomach is a 

 very extensive excavation with a large aperture. 

 Another genus belonging to the South Seas is 

 termed j^quorea. In this the circumference of the 

 disc is furnished with a circle of long filamentous 

 tentacular cirrhi. The under surface is much elon- 

 gated, and in one species, ^quorea cyanea, numerous 

 linear tubes or sacculi radiate from the digestive 

 cavity towards the circumference. Fig. 3867 shows 

 ^quorea cyanea: a, the animal complete; 6, a 

 portion cut away. It is a beautiful species, of a fine 

 azure colour. 



On the coasts of Europe we often see a species of 

 Thaumantias, viz., Th. cymbaloidea. Fig. 386S, in 

 which the marginal tentacles are bulbous at the 

 root ; the digestive cavity is prolonged into a free 

 pedunciiliform appendage divided into canals, 

 and terminated by asimple mouth. Itisof small size. 



In the genus Tinia fhe body is hemispherical 

 with short marginal cirrhi, and produced beneath 

 into a thick conic peduncle, terminated by a pli- 

 cated enlargement ; the oral orifice is at the 

 apex of this conical prolongation, which contains 

 the digestive cavity ; and four tubes run from it to 

 join the marginal canal. 



Fig. 3869 shows the Tima flavilabris, found in the 

 seas of the Azores. 



In the genus Dianoea the body is hemispherical, 

 furnished at its circumference with a small number 

 of tentaculiform cirrhi of considerable length. The 

 under surface is excavated, and from the centre ia 

 continued a proboscidiform appendage, with four 

 rehensile organs at its extremity. 



Fig. 3870 represents a species of Dianaea (Quoy 

 and Gaimard). It is found in the Southern Ocean. 



The genus Favonia has no marginal cirrhi or 

 tentacles, and is rather deeply excavated beneath, 

 whence is prolonged a slender median proboscis 

 surrounded at its root by six or eight fringed ap- 

 pendages, furnished with radiciform suckers. 



Fig. 3871 shows the Favonia octonema, from the 

 Southern Ocean. 



Allied to the preceding genus is that termed 

 Lymnorea : in this genus, however, the hemisphe- 

 rical disc is furnished at its circumference with very 

 fine, short, and numerous tentacular cirrhi. The 

 under surface is excavated, and from the centre 

 depends a long proboscidiform appendage, havin" 

 at its base eight bifid and finely divided filaments.' 



Fig. 3872 represents Lymnorea triedra, from the 

 South Seas. 



We now come to the species with foliaeeous pe- 

 duncles, of which one is represented by the genus 

 Pelagia, in which the body is hemispherical and 

 bloated, and furnished on its circumference with a 

 few long tentacular cirrhi. There are said to be 

 eight inferior oral apertures at the end of a pe- 

 duncle, from which depend four beautiful foliaeeous 

 arms. 



Fig. 3873 represents the Pelagia Labiche (Cyanea 

 Labiche, Quoy and Gaim.). 



Another genus, termed Chrysaora, has fhe body, 

 which is hemispherical, margined by at least twenty- 

 four tentacular cirrhi ; internally it is excavated 

 into a considerable cavity with sacciform appen- 

 dages, communicating externally by a single oi'al 

 oririce, pierced in the centre of a median peduncle, 

 from which depend four long feather-like arms. 

 Fig. 3S74 represents Chrysaora lutea: a, a fourth 

 of the disc, seen from below; b, the disc without its. ' 

 appendages. 



We now turn to a genus of which various species 

 tenant our own shores, viz., Rhizostoma, in which 

 the body is hemispherical with a somewhat lobafed 

 or festooned margin, and largely excavated below. 

 From the centre depends a complex foliaeeous ap- 

 pendage, to which we have already made allusion. 

 Fig. 3875 represents the Rhizostoma Cuvieri, one 

 of the common jelly-fishes of the European seas. 

 It attains to a large size, and weighs several 

 pounds, although, as we have said, when the water 

 contained in the cellular film, and which in some 

 mysterious way is connected with its vitality and 

 the performance of its functions, is drained away, 

 the mass of four, five, or even six pounds scarcely 

 amounts to as many grains. 



3H2 



