HOLOTHURIOIDEA 437 



ground. Development unknown, but apparently it has no 

 Auric 11 laria stage. 



Hitherto known only from off Brittany and Heligoland. 

 That it will occur in the British seas cannot be doubted. 



[II. Subfamily Chiridotin^] 



Deposits of body wall wheels with 6 spokes ; sigmoid bodies 

 often present, sometimes sigmoid bodies alone. 



Only one genus represented in the N.E. Atlantic. 



Chiridota Eschscholtz. 



Tentacles 12. No sigmoid bodies. 

 Wheels collected in papillae. 



One species, Chiridota ahyssicola v. 

 Marenzeller, has been found off the 

 Azores, 2870 m. (" Hirondelle " ; only 

 one specimen known) ; it may well be 

 expected to occur also off the British 

 coasts. The Arctic species, Chiridota 

 Icevis (Fabricius), which is not known 

 farther south than the Lofoten Islands, 

 is scarcely to be expected to occur 

 within the British area. 



[III. Subfamily Myriotrochin^,] 



. Deposits of body wall wheels with 

 many spokes (Fig. 269) ; no sigmoid 

 bodies. 



Three genera are represented in the 

 northern and Arctic seas, namely, ^ca^i- Fig. 268. — Rhahdomolgus 

 thotrochus Dan. and Kor., with the Z'uZ.R^lLJrVbT) 

 species A. mirabilis Dan. and Kor., 



known only from between Norway and Spitzbergen, ca. 1200- 

 2030 m. ; Myriotrochus Steenstrup, with the two species M. 

 Theeli Ostergren, known only from off Jan Mayen, ca. 

 2000 m. ; and M. vitreus (M. Sars) (Sjti. Oligotrochus vitreus 

 M. Sars), kno^vn from ca. 68° N. on the Norwegian coast to 

 Skagerrack, in ca. 100-700 m.i; and Trochoderma Theel, with 

 the species Tr. elegans Theel, known from the Kara Sea to East 



1 A third species of Myriotrochus, M. Rinkii Steenstrup, is an Arctic 

 littoral species which cannot be expected to occur as fai- south as the 

 British area. 



