780 MR. w. E. coLLiNGE ON [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 recep- 

 tacular duct opens, which leads into a large, somewhat pyriform- 

 shaped receptaculum seminis fPl. XLIV. tigs. 8 & 11). The penis is 

 short, though rather longer than that in P. everetti ; the surface oi: 

 its distal end is thrown into a series of ridges (PL XLIV. 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 (PI. XLIV. 

 figs. 3 & 8, r.m.), being below the vas deferens as in P. piipUlaris, 

 Humb. The common duct, consisting of the oviduct and prostate, 

 is wound round upon itself and closely folded. There is a com- 

 paratively 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 (PI. 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 recep- 

 tacular 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 am inclined to regard it, as I have hinted by its 

 name, as an intermediate form connecting the genera Parmarion 

 and Microparmarion, The receptacular duct is considerably 

 shorter than that in P. pnip>iUaris, Humb., figured and described 

 by Simroth\ P. p>upillaris 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. pi. viii. 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 Simroth ^ as 

 follows: — '■'Parmarion s.s. : Die Mantelkante springt stark vor. 

 Die Schale ist eine zarte Kalkplatte, aholich wie bei Limax, mit 

 einer kraftigen glanzenden Epidermis, die sich rechts und links 

 iiber den Rand fortsetzt. Der Liebespfeil ist am Ende in 

 schragem Schlitz geoffnet. Der Penis ist gerade gestreckt, seiu 

 Lumen entspricht in der Form seinem ausseren Umfange. Recep- 

 taculum gestielt. 



^ Microparmanon: Die Mantelkante verwischt sich. Die diinne, 

 von glanzender Epidermis iiberzogene Schalenplatte hat (z. T.) 



1 Op. cit p. lOfi, pi. Tiii. fig. 16. 

 ^ Ov. cit. D. 104. 



Of. cit. p. 104. 



