psoitis. 45 



so as to form a little tail ; mouth and anus terminal or subterminal ; 

 the scales, though often rather large, not prominent, but immersed 

 in the skin ; the integument much more flexible than in P. fahricii. 

 No special oral plates : circumanal plates small. Podia arranged in 

 three irregularly triple rows on the trivium, which is itself a 

 regular oblong, but does Dot extend as far forwards or backwards 

 as the rest of the body. 



To about four and a half inches long, and less than one and a half 

 broad. Colour light, or more or less dark brown. 



The young are much more like P. fahricii than the adult, the 

 mouth and anus being dorsal in position, and the plates far less 

 deeply immersed in the skin. 



Distribution. Both sides of North Atlantic, as far south as Massa- 

 chusetts Bay, and British Isles, and in the Xorth Sea*. To 127 fras. 



a. Firth of Lorn, 50-110 fms. J. Murray, Esq. 



b-f. Coast of Northumberland (dry and in spirit). 



2. Psolus fahricii. (Plate YI. fig. 2.) 



Cuvieria fahricii, Dub. $ Kor. Vet.-Akad. Hdlg. 1841 (1816), p. 316, 



f.n. ; Aijres, Proc. Bost. Soc. X. H. iv. (1854) p. 35; Stimpson, 



Marine Invert. Grand Manan, (1853) p. 16. 

 Psolus fahricii, Semper, Hoi. (1868) pp. 62 & 272 ; Marenzeller, 



Denies. Ah. Wien, xxxv. (1878)' p. 388; Duncan $ Sladm, 



Echinod. Arctic Sea, (1881) p. 10; Lampert, Seewalzen, (1885) 



p. 120; Theel,Chall Rep. Hoi. (1886) p. 128. 

 Lophothuria fahricii, Verrill, Proc. Bost. Soc. X. H. x. (1866) 



p. 364. 

 Holothuria squamata, Fabriciiis, Faun. Granl. (1780) p. 356 ; Gould, 



Inv. Anim. Mass. (1841) p. 340. 



The curved back and vertical sides covered by large overlapping 

 plates, among which are some that are smaller ; as the margin is 

 approached the plates become quite small ; the plates increase in 

 size with the animal ; a special set of smaller, more rod-like plates 

 round mouth and anus, both of which are on the dorsal surface. 

 Podia arranged in an irregular double row round the margin of the 

 foot, a few only extending into the middle line. 



Three inches or more long, about two broad. 



Colour whitish, greyish, or light brown. 



Distribution. Circumpolar, extending as far south as Massa- 

 chusetts Bay ; Shetland ; Japan. 5-148 fms. 



a. Shetland. J. Gwyn Jeffreys, Esq. 



* Dr. Theei (Chall. Rep. 1886, p. 129) gives the British Islands as one of the 

 localities for P. squamatus, and cites as his authorities " Norman, Hodge ; " so 

 far, however, as I am able to understand these excellent authorities, they a<*ree 

 in thinking that all specimens assigned to that species, and said to be of British 

 m*igin. have been wrongly so assigned ; see Norman, Brit. Assoc. 1868 (1869) 

 p. 390, and Hodge, Trans. Northumb. & Durh. iv. (1872) p. 148. 



