THE ANATOMY OP CATJDINA COEIACEA. 457 



latter as more or less elongated, tentacle-like projections, with or 

 without calcareous deposits in their walls. 



In the apodous family Molpadiidce anal papillae have been 

 frequently recorded, and. Ludwig appears to have been the first 

 to suspect * that these structures represent modified tube-feet 

 or ambulacral papillae. To Gerould, however, is due the credit of 

 definitely proving f that the fi^e minute finger-like papillae, which 

 surround the anus in Caudina arenata, are in direct connection 

 with the radial ambulacral vessels and are indeed homologous 

 ■with the terminal tentacles of Asteroids and other Echinoderms. 

 -Grerould also found a pair of short, blind diverticula coming off 

 from the radial ambulacral vessel or canal just in front of the 

 terminal tentacle, and considered, no doubt correctly, that these 

 indicate the former existence of a pair of tube-feet, which now, 

 however, no longer project beyond the surface of the body. 



The remarkable genus Caudina is represented in New Zealand 

 waters by C. coriacea, Hutton. In this species Theel described i 

 the existence of five groups of from five to seven papillae sur- 

 rounding the terminal anus ; one papilla in each group having a 

 very well-developed calcareous skeleton, and possibly representing 

 an anal tooth. He gives, however, no details as to the structure 

 or relations of these organs, and when I first examined the 

 species myself I did not succeed in detecting them §. Since 

 then, however, I have obtained a much more abundant supply of 

 well-preserved material, having found hundreds of young speci- 

 mens II thrown up on the beach at New Brighton, near Christ- 

 church, N.Z., and having also received some interesting fragments 

 of very young specimens dredged by Mr. H. Suter in Lyttelton 

 Harbour. The study of this material has proved that the " anal 

 papillae " in Caudina coriacea are very much better developed 

 than in C. arenata, and has induced me to offer for publication 

 the following account of these interesting organs. 



* Loc. cit. p. 100. 



t Vide Gerould, " The Anatomy and Histology of Caudina arenata" Bull. 

 Mus. Comp. Zool. Harvard, vol. xxix. p. 164. 



I Vide ' Challenger ' Holothurioidea, p. 47. 



§ Vide " Observations on the Holothurians of New Zealand." Journ. Linn. 

 -Soc, Zoology, vol. xxvi. p. 29. 



II One of these specimens is represented of natural size in PI. 29. fig. 13. Ifc 

 is very small as compared with the adult. 



