PSOLUS. 45 
so as toform 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. fabricii. 
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 not 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. fabricii 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, andin the NorthSea*. To 127 fms, 
a. Firth of Lorn, 50-110 fms. J. Murray, Esq. 
b-f. Coast of Northumberland (dry and in spirit). 
2. Psolus fabricii. (Plate VI. fig. 2.) | 
Cuvieria fabricii, Dib. § Kor, Vet.-Akad. Hdlg. 1844 (1846), p. 316, 
fn.; Ayres, Proc. Bost. Soc. N. H. iv. (1854) p. 35; Stimpson, 
Marine Invert. Grand Manan, (1853) p. 16. 
Psolus fabricii, Semper, Hol. (1868) pp. 62 & 272; Marenzeller, 
Denks. Ak. Wien, xxxv. (1878) p. 388; Duncan § Sladen, 
Echinod. Arctic Sea, (1881) p. 10; Lampert, Seewalzen, (1885) 
p. 120; Théel, Chall. Rep. Hol. (1886) p. 128. 
Lophothuria fabricii, Verrill, Proc. Bost. Soc. N. H. x. (1866) 
. 804, ; 
Helens squamata, Fabricius, Faun. Grenl. (1780) p. 356; Gould, 
Inv. Anim. Mass. (1841) p. 846. 
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, afew 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. Théel (Chall. Rep. 1886, p. 129) gives the British Islands as one of the 
localities for P. sguamatus, and cites as his authorities “‘ Norman, Hodge ;” so 
far, however, as I am able to understand these excellent authorities, they agree 
in thinking that all specimens assigned to that species, and said to be of British 
origin, have been wrongly so assigned ; see Norman, Brit. Assoc. 1868 (1869), 
p- 396, and Hodge, Trans. Northumb. & Durh, iv, (1872) p. 148. 
