1882. ] PROF. F. J. BELL ON THE GENUS PSOLUS. 647 
would have probably found themselves associated with P. fabricii 
had they not borne Mr. Norman’s name. So far as can be gathered, 
no further information is accessible as to the early stages of the “‘tailed”’ 
species ; and till such evidence or intermediate forms are to hand, it 
would perhaps be well not to use the information as undoubtedly 
exact ; at the same time it is quite certain that, as they got the infor- 
mation from specimens determined by Mr. Norman, Messrs. Duncan 
and Sladen were fully justified in noticing it. 
Psotus (LopHoTHuRIA) PERONII, n. sp. (Plate XLVIII. 
fig. 1.) 
Form elongated, rounded, no caudiform prolongation; back and 
sides evenly rounded ; neither oral nor anal region specially promi- 
nent ; median row of suckers confined to three or four pairs at either 
end, 
The body is covered by a very large number of scales, set pretty 
regularly in rows, only slightly imbricated near the margin. The 
scales may be covered completely by granules; or the central portion 
may be bare of them; or the whole scale may be free from granules, 
which may be found only around it. The irregularity presented by 
the scales is to be observed also in the oral and anal plates; as the 
covering-plates converge towards the mouth, some become larger, 
barer, and more tubercular in appearance: the same obtains with the 
anal region; but there is a very large amount of variation in the 
appearances produced. 
The retractors of the pharynx are very long ; the joints of the cal- 
careous ring are well developed (Plate XLVIII. fig. 1 6) ; and there 
is a large saccular Polian vesicle. 
The spicules from the integuments of the “‘ foot” are of very much 
the same character as in P. phantapus; but the projecting spokes are 
rather long. They vary considerably in size (fig. 1 c). 
Measurements :—length 60, 56, 55 mm. 
breadth 34, 561, 40 mm. 
height 23, 33, 23 mm. 
Length of Polian vesicle (at least), 8, 11 mm. 
No definite locality can be given for the species; some of the spe- 
cimens from the Haslar Hospital are stated to have been collected 
by Berthold Seemann. I have not been able to forma very clear idea 
of P. operculatus (Pourtalés) ; there is no doubt, of course, that 
it belongs to the Lophothurian subgenus: a number of specimens 
would seem to have been collected; and we may therefore presume 
that it is a rather small species (the length given by Pourtalés being 
13 inch, and the breadth 3 inch). P. peronii runs very much larger 
than this, and it is at least twice its size. So, again, the colour of 
P. operculatus is said to be light grey ; this is not the case with 
P. .peronii, for the pale yellow of some specimens is replaced by dark 
brown in others. 
 Contorted. 
