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Show 1 9 0 3 . ] POLYCLADS OF THE " SKEAT EXPEDITION." 3 1 5 in fig. 10 of Plate XXIII. The tentacles also in Collingwood's species are much more prominent. The penis is unpaired. The body is nearly circular and the sucker median. Total length about 5 mm., breadth 4 mm. The arrangement of the eye-spots is very different from that normally found in Pseudoceros, but I cannot find any other characters distinguishing it from that genus. At least two other species of this genus are represented in the collection. One of these is a very small individual of the P. supei'bus-group (perhaps P. hancockianus); whilst several specimens belong to a species coloured exactly as Proceros con-cinnum Coll., viz., they are blue, with orange margin and median stripe. They are, however, very much smaller, about 8 mm. to 10 mm. in length, and of a different shape, not pointed at their hinder end, and have small, folded tentacles, whereas Collingwood's species has pointed tentacles. Proceros concinnum in fact is almost certainly a Euryleptid, whilst these specimens are undoubtedly members of the genus Pseudoceros. I prefer, however, not to name them at present. Family D ip o s t i i i id ^e . A sthenoceros, gen. nov. A sthenoceros w o o dw o r t i i i , sp. n. (Plate XXIII. fig. 7.) Two specimens, without notes as to colour ; but, to judge from these spirit-specimens, the species is of a reddish-brown colour, darkest on the middle line. Length, about ... 17mm. Breadth..................14 ,, Mouth-opening... 7 ,, from the anterior margin. Sucker ..................1*5 ,, behind mouth. The male and female apertures lie in the usual order between the " mouth" and sucker. The pharynx is large and much folded, its opening being submedian. This feature will serve at a glance to distinguish this species from any of the Pseudoceridre. In describing the type of the family, Woodworth [16] makes no statement as to the pharynx, but, to judge from the figure given, it is median or submedian as in the present species. The bod}*- is flat and almost circular; the anterior margin is feebly folded, and there is a small group of eye-spots on either side of the middle line, but there are no very definite tentacles. The prostate body lies in front of the penis. In this respect Asthenoceros differs from the type-genus Dipos-thus. There are no brain-eyes. Only one of the two specimens was cut into sections, transversely ; the other specimen appeal's, from an examination of it when cleared in oil of cloves, to be quite immature. The specimen serially cut presents certain peculiar features, which I am at |
