HOLOTHURIOIDEA 



385 



occur there, and sometimes they are as numerous as, or even more 

 numerous than, in the lateral ambulacra. On the dorsal side 

 scattered, more or less distinctly serially arranged, larger papillae. 

 Calcareous deposits (Fig. 229) cruciform bodies, with one or more 

 holes in the end of each branch ; in the centre a high spire formed by 

 4 rods connected by a variable number of cross beams. C-shaped 

 spicules may be found in the skin or in the inner organs. Colour 

 in life yellowish, faint reddish, or brownish ; yellow spots between 

 and on the tentacles. Grows to a size of ca. 15 cm. 



The variable development of the tube -feet on the ventral sole 

 has caused the establishment of the supposed species B. Tizardi 

 and fallax ; but as all transitional forms may be found, even in one 

 and the same locality, the said forms must be regarded only as 

 individual variations of B. natans. 



Fig. 229.- 



-Calcareous deposits of Bathi/plotes natans. 

 (From Danmark's Fauna.) 



xUo. 



1-2. Cruciform bodies, from above. 3. Same, in side view. 4. Smaller form of cruciform 

 bodies, with branclies partly connected by transverse rods. 5. C-shaped spicule. 



It is unisexual. Eggs large, yolky ; the development, there- 

 fore, probably direct. An observation from Japan seems to 

 indicate that it is brood-protecting, the male carrying the eggs 

 attached to its tentacles. It swims by means of up and down 

 movements. It has the peculiarity (probably common to various 

 species of the genus) that the skin easily breaks up along the 

 interradii. If kept alive for a little while, the skin is apt to 

 dissolve into slime. It lives on muddy bottom, feeding — like all 

 these deep-sea Holothurians — on detritus. 



In British seas this species has been found in the Faroe 

 Channel ("" Triton '") and off the Irish west coast ("' Flying Falcon", 

 " Helga "), 1100-1350 m. It is elsewhere distributed from Lofoten 

 to the Cape Verdes ; also recorded from the West Indies and from 

 Japan. Bathymetrical distribution ca. 200-1600 m. 



2c 



