ECH1NODERMS. 129 



the spaces between the rays. In the disciform genus Culcita, the 

 appendages of the rectum are greatly developed, five in number, 

 each divided into two branches, and clustered 1 . In Ophiura and 

 Euryale the csecal stomach has lateral recesses, or even branched 

 blind appendages, mostly ten in number, which, however, do not 

 penetrate the rays. In Comatula the intestinal canal is tubular, 

 and winds round a spongy structure in the axis of the disc ; from 

 this an edge projects, that penetrates into the canal and forms a 

 valve 2 . In the sea-urchins (Echinus} the intestinal canal is very 

 long. The oesophagus is tortuous, narrow, and beset with numerous 

 follicles. Where it passes into the much wider intestinal canal, 

 there is a csecal appendage. The walls of the canal are very thin : 

 its course is close to the shell in five arcs directed outwards ; when 

 it has returned nearly to the point from whence it began, it bends 

 round and follows a similar route in an opposite direction, until at 

 last, having become somewhat narrower, it mounts up to the anus 

 (at the uppermost part of the shell). In the Holothurice the intes- 

 tinal canal is nearly of the same width throughout. It proceeds 

 from the mouth along one side of the body to the lower extremity, 

 then bends back to the anterior part, and finally descends along the 

 other side to the cloaca, into which the respiratory organs also 

 open. In Echiurus the intestinal canal is, in like manner, mucli 

 longer than the body, and makes many convolutions : it has numer- 

 ous cystiform widenings, and very thin walls. In $ipunculus, 

 where the anus is placed not at the end, but in the anterior half of 

 the body, the intestinal canal, with its threefold bending, is nearly 

 four times the length of the body. In Synapta, on the other hand, 

 it is nearly straight, and about the length of the body, the anus 

 being at the posterior extremity 3 . In the star-fishes probably the 

 radiating appendages are to be considered as organs for preparing 

 bile (liver) : they are filled in Ast. rumens with a yellow turbid 

 fluid 4 . 



1 J. MUELLEB und F. H. TBOSCHELL, System der Asteriden. Braunschweig, 1842, 

 4to, s. 132. Taf. XIT. fig. i. 



2 J. MUELLER, Abhandl. derBerl Akad. a. d. J. i%4i,Physik.Kl. Tab. v. f. 710. 



3 QUATBEFAGES, Ann. dcs Sc. nat. sec. se'rie xvn., Zoologie, p. 51. 



4 Other -writers consider the blind appendages at the bottom of the stomach or at 

 the rectum as a rudiment of liver. OWEN, Led. on the Comp. Anat. of invertebr. 

 Animals, 1843, p. 115. In these appendages a rudimentary form of kidney might also 

 be recognised, an opinion, however, which does not rest on chemical investigation. 



VOL. I. 9 



