CIRRIIOPODA. 



C89 



Fig. 340. 



Fig. 341. 



stomachs, and Burmeister once found part of 

 an annelid of unknown species. The food is 

 carried towards the mouth by currents pro- 

 duced by the rapid motions of the arms, 

 which, in most of the 

 species, are constantly 

 spread out and drawn 

 in, alternately, with 

 great regularity. The 

 mouth is situated just 

 at the bottom of the 

 funnel - shaped cavity 

 formed by the spread 

 arms ( b,fig. 340). In 

 the Lepads its position 

 is close to the trans- 

 verse adductor muscle. 

 Its jaws form a round 

 protuberance, which 

 presents itself very con- 

 spicuously immediate- 

 ly on separating the 

 arms. It might al- 

 most be regarded as a 

 head, so prominent is 

 it (fig. 341, />,&); but we find it 

 composed only of the lip and 

 jaws, with their muscles. The 

 lip over-arches the jaws ; it is 

 horny, and furnished with minute 

 palpi. There are three pairs of 

 jaws. The first or outer pair are 

 thin horny plates of an oval form, 

 fringed along their opposing sides 

 with long stiff hairs. The other 

 two pairs are curved and deeply 

 serrated on their opposed surfaces. 

 The middle pair bears a small 

 palp on its lateral margin. In 

 some species, a small tongue has 

 been found. All these parts bear a close re- 

 semblance to the same organs in some of the 

 Crustacea. The oesophagus is short ; its lining 

 membrane is somewhat horny, stiff enough 

 permanently to distend the whole canal ; be- 

 fore entering the stomach, its diameter is con- 

 siderably enlarged. It receives the ducts of 

 two salivary glands. The stomach (c,fig. 341) 

 is capacious; externally, it presents an irre- 

 gular mamillated surface, studded with nu- 

 merous small prominences closely set, which 

 are the outer surfaces of hepatic cells, formed in 

 a layer of glandular tissue that closely in- 

 vests the walls of the stomach. These cells 

 communicate directly with its general cavity 

 (, fig. 342). There is no other organ that can 

 be regarded as a liver.* Two coscal appen- 



* Burmeister's recent researches have led him 

 to conclude that both the Lepads and the fialanids 

 have large livers. He has satisfied himself that 

 the organs, regarded by Cuvier as the ovaries, 

 and by more recent authorities as the testicles, 

 communicate by ducts with the upper part of the 

 intestinal canal, and not at all with the seminal 

 vessels. Hence he supposes that they are lobes 

 of the liver and not organs of reproduction. Our 

 own dissections lead us rather to agree with 

 Messrs. Wacner and St. Ango, who believe them 

 to be the tesncles. 



d;i;vs, also saccu- Fig. 342. 



lated internally, and ,^ _^> 



embossed outwardly, 

 are attached to the 

 stomach. 



The intestine is 

 wide, nearly without 

 convolutions, and ta- 

 pering towards the 

 anus (d,e y fig. 341). 

 In the Lepads the 

 stomach is situated 

 in that part of the 

 visceral mass near- 

 est to the peduncle ; 

 from which point the 

 intestine runs on the dorsal aspect of the body, 

 and terminates in the anus just at the base of 

 the articulated tubular process. It is slightly 

 dilated near the anus. The walls of the in- 

 testine are perfectly smooth and free from folds 

 and duplications. The number of their tunics 

 cannot be satisfactorily determined. M. St. 

 Ange has described a singular piece of struc- 

 ture which he has found within the intestinal 

 canal of certain Anatifae (c, c, fig. 342). It is 

 a kind of second intestine, which floats within 

 the cavity of the one just described. It is 

 nearly equal in length to the outer canal. Its 

 upper extremity is expanded, funnel-shaped, 

 with edges cut into fringed processes like the 

 mouths of the Fallopian tube in vertebrate 

 animals. These processes are lodged in the 

 cells of the walls of the stomach, and furnish 

 the only means of attachment to the outer 

 walls with which the organ is provided. It 

 thence tapers towards the anal extremity, 

 where it is pointed and closed. Its walls are 

 very thin and delicate. It is generally filled 

 with alimentary matter, which must pass from 

 its cavity by a kind of rumination, so as to 

 enter the stomach a second time. 



Circulation. The sanguiferous system of the 

 Cirripeds has not yet been fully investigated. 

 Only the vessels of the arms, and a central 

 canal, situated on the dorsal aspect of the body, 

 have been discovered. Poli asserted that he 

 saw a heart pulsating a little above the anus : 

 but it does not appear that any other observer 

 has made the same remark. Burmeister has 

 searched, in vain, for a heart, in the large Coro- 

 nula diadema. The vessels of the arms can be 

 distinctly seen through the transparent integu- 

 ments of the ciliated processes ; there are, in 

 each process, two vessels, one of which runs 

 very superficially between the two rows of 

 hairs. ( Fig. 343.^ 



Cuvier regarded the anterior canal of the 

 peduncle in Anatifa as the nourishing vessel of 

 that organ. 



Respiration. The principal organs concern- 

 ed in respiration are, in the Lepads, certain 

 tapering filamentary processes attached to the 

 sides of the anterior part of the body, which 

 are regarded as the branchiae (d, g, fig. 340) : 

 in most of the Balanids, they assume the form 

 of two leaf-like membranes with fringed mar- 

 gins, and are attached to the inner surface of 



