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Show 780 MR. w. E. COLLINGE O N [June 15, which the vagina opens as a thick-walled tube; at the junction of the tube-like portion with the wider cavity, a very short receptacular duct opens, which leads into a large, somewhat pyriform-shaped receptaculum seminis (Pl. X L I V . figs. 8 & 11). The penis is short, though rather longer than that in P. everetti; the surface of its distal end is thrown into a series of ridges (Pl. X L I V . fig. 9 r): these are more conspicuous on the ventral side. The vas deferens passes off from the ventral side, as shown in fig. 9. The retractor muscle has its attachment much lower than in P. everetti (Pl. XLIV. figs. 3 & 8, r.m.), being below the vas deferens as in P. pupillaris, Humb. The common duct, consisting of the oviduct and prostate, is wound round upon itself and closely folded. There is a comparatively small albumen-gland. The hermaphrodite gland is a small oval-shaped body, attached to a densely convoluted tube, the hermaphrodite duct. The dart-sac is a large, thick muscular-walled organ, slightly twisted at its lower end. The dart (Pl. XLIV. fig. 10) is an irregular shaped body, solid throughout, non-calcareous, broad at its base and tapering at its free end. Affinities. The shape and size of the dart-sac and dart, the short receptacular duct, the position of the opening of the vas deferens into the penis, and the minor differences in the form of the penis and vagina, separate P. Intermedium from any other known species of this genus. I a m inclined to regard it, as I have hinted by its name, as an intermediate form connecting the genera Parmarion and Micropannarion. The receptacular duct is considerably shorter than that in P. pupillaris, H u m b . , figured and described by Simroth1. P. pupillaris is undoubtedly its nearest ally, but it differs from this species in the shorter length of the receptacular duct, the large and pyriform-shaped receptaculum seminis, the position which the duct opens into the vagina, the shape and size of the dart-sac and dart (cf. Simroth, op. cit. pl. vni. fig. 17), and the minor differences, such as the position which the vas deferens opens into the penis, the shape of this latter organ and the albumen-gland, &c. The characters of these two genera are described by Simrotha as follows:-"Parmarion s.s.: Die Mantelkante springt stark vor. Die Schale ist eine zarte Kalkplatte, ahnlich wie bei Llmax, mit einer kriiftigen glanzenden Epidermis, die sich rechts und links uber den Band fortsetzt. Der Liebespfeil ist a m Ende in schragem Schlitz gebffnet. Der Penis ist gerade gestreckt, sein L u m e n entspricht in der F o r m seinem iiusseren Umfange. Becep-taculum gestielt. " Mlcroparmarlon: Die Mantelkante verwischt sich. Die diinne, von glanzender Epidermis iiberzogene Schalenplatte hat (z. T.) 1 Op. cit. p. 106, pl. viii. fig. 16. 2 Op. cit. p. 104. |