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Show 1897.] NON-MARINE FAUNA OF SPITSBERGEN. 795 Some few remarks 'are added on the most interesting details relative to the rarer forms, whilst brief descriptions are furnished for one species, not hitherto described, but which I had previously seen in England, and for one other which it has been necessary to rename. Order BDELLOIDA. 1. PHILODINA ERYTHROPHTHALMA, Ebr. It is wdth some little doubt that I refer to this species a form which is very closely related to Philodina cltrlna, and differs from it principally in the size of the mastax (rami, 0*022 m m . long) and in the shape of the egg (oval, symmetrical and smooth). The species is included in Bergendal's list, but it is impossible to affirm that the form seen by him is identical with that now found, for, although described by Ehrenberg as the commonest of the genus, the species is at the best an unsatisfactory one, the original description being exceedingly meagre. Gosse has given fuller details of a form which he thought he could refer to it, but these have not been found useful to establish the identity even of the subject of his description. The species has been noted again and again in local lists, but never with any attempt at better definition of its identity. On the other hand, Janson (6), when he wrote his paper on the Phllodlncea, had failed to discover any form which he could assign to it, and he rejected it as invalid, and hitherto neither I nor several experienced correspondents have been more successful. It would however appear, from the very meagreness of Ehren-berg's description, that the species should be closely related either to P. cltrlna or to P. roseola, and this postulate is fulfilled by the Spitsbergen examples, whicb when adult might easily be passed over as P. cltrlna, varying from the type in lacking the distinctive colour of that species. Closer examination, however, reveals several structural differences (minute, but constant in many examples), of which those mentioned above are themselves sufficient to establish specific rank. In young examples the corona is barely wider than the collar, and has a rather smothered appearance, which disappears as the animal approaches maturity. In habits it resembles P. roseola, being decidedly restless, and even when feeding it is incessantly changing its position. From its behaviour in the trough I judge it to be a "bottom-feeder," and to prefer feeding from a swinging base (as from a mucus thread) rather than from a firm one. 2. PHILODINA sp. Some specimens with very coarse skin with prominent skin-folds, whose ridges were broken and wrinkled, were referred to a form recently discovered by Forstmeister L. Bilfinger of Stuttgart, and to be described in a paper now in preparation. 3. BOTIFER TARDUS, Ehr. A single specimen. |