HOLOTHURIOIDEA 



383 



peripheral holes of the disk, has been designated Var. oxysdera 

 Perrier. 



In British seas this species has been found off S.W. Ireland, 



Fig. 227. — Deposits of Mesothuria lactea. x 275. 

 (After Perrier, " Talisman " Holotk.) 



in depths of ca. 1200-1765 m. (" Helga "). It is elsewhere 

 distributed from the Bay of Biscay to the Azores and Cape 

 Verdes, and also recorded from the Indo-Pacific. The bathy- 

 metrical distribution is ca. 700-2100 ni. 



2. Bathyplotes Ostergren. 



Body flattened on the ventral side, which forms a distinct 

 sole, a more or less conspicuous fringe limiting it from the dorsal 

 side. Skin rather thick. Mouth ventral. Fifteen to twenty 

 tentacles. Tube-feet well developed on ventral side, but often 

 lacking in the mid- ventral radius ; papillae on the dorsal side. 

 Deposits cruciform, with spire ; C-shaped spicules may be 

 present. Gonads on both sides of dorsal mesentery. 



One species known from the British seas, but two more ma}^ 

 possibly occur there also, namely BathyjAotes Pourtalesii Theel 

 (Syn. B. bipartitus Her.),i found off the Cape Verdes, 134-1477 m. 

 (" Princesse Alice "), also known from the West Indies, 375- 

 1320 m. ; B. reptans Perr., 30° 3' N., 14° 2' W., 2212 m. 

 {" Talisman "). 



^ According to Miss Deichmann, who has had the opportunity of 

 studying more closely the Bathypl. Pourtalesii. 



