STELLEEIDEA. 



293 



situate inter-radially and upon the dorsal surface. The multilobed 

 branched diverticula of the stomach extend into the cavities of the 

 arms (fig. 218). On the ventral surface of the latter, two or four 

 rows of ambulacral feet project from the deep ambulacral groove, 

 the edge of which is beset with papillae (fig. 235). Pedicellarice are 

 also found, and dermal gills projecting through the tentacular pores 

 of the dorsal surface. 



They feed principally upon Mollusca, and, by means of their 

 ambulacral feet, crawl slowly upon the bottom of the sea. Some 

 few of them are developed by a very simple process of metamorphosis 

 within the brood-pouch of the mother; but the greater number of 

 them pass through the free 

 larval stages of Eipinnaria 

 and Brachiolaria (figs. 224 

 and 228). 



Fam. Asteriadae. The cylin- 

 drical ambulacral feet end in 

 broad suctorial discs, and are 

 usually arranged in four rows 

 along each ambulacral groove. 

 Astcrias L. (_Asteracant7iion), 

 A. glacialis O. F. Miiller., Ile- 

 liattci' Jielianthiis Gray. 



Fam. Solasteridae. The cylin- 

 drical ambulocral feet are dis- 

 posed in two rows. Rays long, 

 often more than five Solaster 

 j>nj>2}o,<n/s Retz., Echinaster 

 sejjoxiti/s Rctz., Ophidiaster 

 Ag., Llncltia Nardo. 



Fam. Astropectinidse. Am- 

 bulacral feet conical, and with- 

 out suctorial disc, arranged in two rows. There is no anus. 

 aurantlacus Thil. Luidia Forb., Ctcnodisciis Miill. Tr. 



Fam. Brisingidae. Body shaped like an Ophiurid. Rays distinct from the 

 disc with only a narrow internal cavity. Brisinga coronata Sars. 



FIG. 237.- Atterisciti verriteuJatu*, with the dorsal 

 skin removed. Ld, RaJial appendages or hepatic 

 tubes of the stomach ; G, generative glands. 



Astropectcn 



Sub-Class 2. OPHIURIDEA (Brittle Stars). 



Asteroidea characterised by the absence of an anus, and by the pos- 

 session of long cylindrical arms which are sharply distinct from the 

 disc, and do not contain appendages of the alimentary canal. The 

 ambulacral groove is covered by the dermal plates so that the ambulacral 

 feet project at the sides of the arms. 



The Ophiuridea can be at once distinguished by the flexible 

 cylindrical arms, which are sharply distinct from the disc, and enclose 



