172 THE APODOUS HOLOTHUBIANS 



REMARKS. This unique species is based on a single incomplete individual, 

 which is so well characterized by its calcareous deposits that it could not be as- 

 signed to any other species. Besides the tables and the remarkable anchor- 

 plates, which usually have three rather long arms, numerous phosphatic de- 

 posits are present. The caudal portion of the type specimen was lost or de- 

 stroyed when it was taken. 



MOLPADIA TKIDENS 



PLATE X, FIGS. 8, 9. 

 Ankyroderma tridens Sluiter, 1901, p. 122. Calcareous particles, pi. x, fig. 7. 



LENGTH. Up to 80 mm., of which the tail is about one-fourth. 



COLOK. Gray, with numerous small red-brown spots. 



DISTRIBUTION. Reported only from the Dutch East Indies, 330-462 m. 

 (Sluiter). 



REMARKS. This is a most interesting species, remarkable for the absence 

 of all calcareous deposits save anchors and plates and the presence of numer- 

 ous phosphatic deposits, thus reversing the usual condition, where numerous 

 phosphatic deposits are associated with the disappearance of anchors and 

 plates. Sluiter 's account of the appearance of the deposits is further evidence 

 to show that calcareous particles in Molpadia become transformed into the col- 

 ored phosphatic bodies. 



MOLPADIA POLYMORPHA. 

 PLATE X, FIG. 25. 



Ankyroderma polymorphism Koehler and Vaney, 1905, p. 103. Calcareous particles, 

 pi. xiv, figs. 14-19. 



LENGTH. 50 mm., of which the tail is 15 ; the diameter of the body is only 

 10 mm. 



COLOR.- White, tinged with reddish. 



DISTRIBUTION. Reported from the Gulf of Bengal, 1,242-1,656 m. (Koehler 

 and Vaney). 



REMARKS. As only a single specimen of this form was taken, one cannot 

 avoid the suspicion that it may be only a young and aberrant concolor. It is 

 impossible to tell from the description given whether the anchors are associated 

 with a single plate or with a rosette of such plates. 



CAUDINA Stimpson, 1853. 

 Molpadia Miiller, 1850; Semper, 1868; non Cuvicr, 1817. 



Tentacles 15, with 2 pairs of digits, the distal pair longer than the proximal ; 

 no terminal unpaired digit. Body rather stout, more or less tapering posteri- 



