THE APODOTTS HOLOTHUBIANS 169 



COLOR. Yellowish gray, often with a violet tinge, especially anteriorly; in 

 some specimens the violet color is very marked. 



DISTRIBUTION. Reported from off Grenada, 749-996 m. (Theel) ; south of 

 Nantucket, 2,695 m., and Caribbean Sea, 1,613 m. (Clark). 



REMARKS. The difference between the calcareous deposits of this species 

 and arctica is so obvious and apparently so constant that it does not seem likely 

 the two species can be identical. In some specimens of parva the tables are re- 

 markably uniform in having only 3 holes in the disc. Such tables resemble in 

 form those of blakei, but are very much larger and the spire is much lower in 

 proportion. 



MOLPADIA ARCTICA. 



Haplodactyla arctica v. Marenzeller, 18776, p. 29; pi. iv, fig. 1. 

 Trochostoma arcticum Danielssen and Koren, 1879, p. 126. 

 TrocHostoma boreale Ludwig, 1900<z, partim. 



LENGTH. Up to 190 mm. when fully extended, of which the tail is scarcely 

 one-tenth; diameter about 30 mm. 



COLOR. Whitish, grayish or brownish gray, more or less strongly tinged 

 with violet. 



DISTRIBUTION. Reported from north of Nova Zembla (v. Marenzeller) ; 

 Kara Sea (Theel) ; Finmark (Danielssen and Koren). Apparently an Arctic 

 species, confined to the cold waters north of Europe. 



REMARKS. Ludwig 's opinion that this species is identical with boreale 

 Danielssen and Koren does not seem to me justified by the material at hand. 

 The skin in arcticum is thin and rough and always lacks phosphatic deposits, 

 so that the general appearance is quite different from the other Arctic species. 

 So far as recorded, no specimens have been taken which are evident connecting 

 links between the two forms, and for the present at least it seems to me they 

 ought to be kept separate. So far as known, this species never has anchors or 

 rosettes. 



MOLPADIA AGASSIZII. 

 Ankyroderma agassizii Theel, 18866, p. 19. 



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



COLOR. Light grayish, inclining to violet. 



DISTRIBUTION. Reported only from Bequia, 2,712 m., and from an unknown 

 West Indian station, 1,904 m. (Theel). 



REMARKS. This notable species is well characterized by its thin, rough, 

 brittle body-wall, rilled with perforated plates. There are also tables, some- 

 what like those of arctica, present, and anchors and rosettes. The rods mak- 

 ing up the rosettes have the large end perforated with 25 or more holes. A 

 thick layer of fusiform supporting rods with the middle enlarged and per- 

 forated is found in the tail. 



