THE APODOUS HOLOTHURIANS 185 



on the tentacles, the presence of a prominent genital papilla, the smaller 

 number of dorsal pai)il]a', and the presence of rudimentary pedicel-like out- 

 growths. None of these differences, however, will stand very critical examina- 

 tion, and if the two species are shown, by the collection and study of further 

 material, to be alike in the presence or absence of a caudal appendage, it seems 

 to me very probable that they are congeneric, and Himasthlephora must be- 

 come simply a synonym of Gephyrothuria. As regards the relationship of these 

 interesting holothurians to other genera, it seems to me clear that they are 

 closely related to Caudina, although in the unpaired longitudinal muscles, the 

 absence of tentaele-ampuUs, of posterior prolongations on the radial pieces of 

 the calcareous ring, and of phosphatic deposits they resemble Eupyrgus. They 

 certainly belong to the Molpadiidae. The number and form of the tentacles and 

 the general appearance is very characteristic, and the presence of rudimentary 

 ambulacral appendages is not of nearly sufficient importance to warrant the 

 formation of a new family. Gerould ('96) long since demonstrated their pres- 

 ence in Caudina arenata. It might be possible to form a subfamily of Himas- 

 thlephora and Gephyrothuria, but in the present imperfect state of our knowl- 

 edge of these forms, such a step seems to me inadvisable and undesirable. 



Himasthlephora glauca. 

 Plate XIII, Figs. 1-4. 

 Himasthlephora glauca Clark (antca, p. 40). 



Length. — 28 mm., of which 9 is tail ; diameter about 8 mm. 



CoLOK. — Uniform pale gray ; tentacles and genital papilla brownish. 



Distribution. — Reported only from "Albatross" Station 2678, off the coast 

 of Georgia, 1,316 m. .(Clark). 



Remarks. — Nothing remains to be added to the remarks on page 41, save 

 that this species appears to be much smaller and more dully colored than the 

 following, although the specimens were apparently sexually mature. They oc- 

 curred on a bottom of "light gray ooze," with which they must have corre- 

 sponded in color almost exactly. 



GEPHYROTHURIA Koehler and Vaney, 1905. 



Tentacles 15, with only two (?) digits, without ampullae. Body nearly 

 cylindrical, rather stout, with no caudal portion (!). Mid-dorsal interambula- 

 crum with 7-9 whiplash-like pai)illa?. Pedicel-like outgrowths and genital papilla 

 wanting. Calcareous ring without posterior prolongations. Calcareous and 

 phosphatic deposits wanting. 



The peculiarities of this genus have been fully discussed in connection with 

 the preceding, to which it is at least most closely related. 



