EEPOKT ON THE HOLOTHUEIOIDEA. 
127 
ha\Tng a nearly uniform layer of innumerable minute, perforated plates, over 
which are scattered numerous round granules. Deposits of the sole like those 
in the dorsal surface, though less in quantity. 
Habitat . — Banks of Newfoundland, George’s Bank (Ayres). 
According to Ajures the plates of the dorsal surface bear a strong resemblance to 
those in Stcreoderma unisemita, being oval, smooth and usually pierced with four 
holes. 
Psolus ornatus (Lissothuria), Verrill, 1867-1871. 
Body elongated, depressed, with the flat lower surface broad. Anal region not very 
prominent. Pedicels numerous, forming six to eight rows in each longitudinal 
series. The soft dorsal perisome filled with minute grains, and fewer, some- 
what larger, perforated ones. Ptound the naked part of the body below the 
tentacles, a ring of calcareous plates with pointed ends. 
Habitat . — Panama (Verrill). 
The species is unsatisfactorily known, and needs re-examination. 
2. Dorsal integument supported by large scales. 
Psolus phantapus {Holothuria) , Strussenfeldt, 1765; Jaeger, 1833. Ascidia rustica, 
Pennant, 1777. Cuvieria phantapus, Fleming, 1828 ; Diiben and Keren, 
1844. Psolus IcBvigatus, A}Tes, 1854. 
Body subcylindrical, Hsc^Zm-shaped, with each extremity turned up ; anal region 
elongatedly conical, caudiform. Sole rectangular. The lateral series of pedicels 
composed of two to three rows ; the odd ambulacrum, at least in its middle, 
with only a simple row. The thick leathery dorsal integument with large 
granulated scales imbricating upon one another. The sole strengthened by 
reticulate cups and spheres. 
Habitat . — West coast of Scandinavia from the Sound to Finmark (0. F. Muller, 
Danielssen and Horen, Ltitken, Mobius and Biitschli, Sars, Diiben and Koren, 
Mobius, &c.); Spitzbergen (Ljungman), Arctic Sea north from Norway (Hoffmann), 
Greenland (Ltitken, Fabricius, Duncan and Sladen, &c.). White Sea (Jarzynsky), 
Iceland (Ltitken), British Islands (Hodge, Dalyell, Ltitken, MTntosh, Forbes, 
Leslie and Herdman, Norman); east coast of North America, Banks of New- 
foundland and Cape Cod (Ayres), Grand Manan (Stimpson), Chelsea Beach, 
Mass., Mount Desert, Eastport, Maine-, Massachusetts (Verrill). 
(Mus. Holm.) A great number of specimens from different localities of ScandinaAua. 
Psolus complanatus, Semper, 1868. 
Body very much depressed. The lateral series of pedicels composed of four to six rows ; 
the odd series, on the contrary, made up of two to three rows. The number of 
