OCR Text |
Show 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 information from specimens determined by Mr. Norman, Messrs. Duncan and Sladen were fully justified in noticing it. PSOLUS (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 prominent ; 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 calcareous ring are well developed (Plate XLVIII. fig. 1 b) ; 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, 56\ 40 m m. height 23, 33, 23 m m. Length of Polian vesicle (at least), 8, 11 m m. No definite locality can be given for the species; some of the specimens from the Haslar Hospital are stated to have been collected by Berthold Seemann. I have not been able to form a very clear idea of P. operculatus (Pourtales) ; 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 Pourtales being 1^ inch, and the breadth -f 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. 1 Contorted. |