264 PEOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



A particular feature of this Rystem of organs (Fig. I) is the long 

 vestibule, which is much like that of Pleurodonte {Caprinus) 

 orhiculata shown in Pilsbry's figure, but not mentioned in his 

 description.^ 



On the other hand, T. lygcea, as well as several nearly allied 

 species, T. conisalea, Melv. & Pons., T. Burnupi, Melv. & Pons., and 

 T. aulacophora, Ancey, do not possess the spiral striations on the apex 

 of the shell cited as a character of Trachycystis by Pilsbry,'^ nor, again, 

 have the inner marginal teeth of the radula the remarkably long 

 entocones (Fig. II) figured by Pilsbry,^ while anything like the 

 numerous flat plaits on the jaw mentioned in the same work can 

 only be seen when it is greatly magnified (Fig. III). 



2. DOKCASIA GLOBULUS, MuLL. 



The figure given by Pilsbry of the genitalia of Borcasia Alexandria 

 was from a badly preserved specimen, and shows signs of immaturity, 

 SO that the drawing (Fig. lY) of a dissection prepared from examples 

 of Borcasia glolulus is worthy of note. The specimens which supplied 

 material for this note came from Eobbin Island (Cape of Good Hope), 

 and were furnished in this case also by Mr. Ponsonby. Several 

 interesting peculiarities were met with. In the two species 

 mentioned the organs are much alike, but the way in which the 

 various structures were found to be interwoven in the latter is 

 rather remarkable. 



The vagina swells after the separation of the male and female ducts, 

 and this swelling is outlined upon one side by the vas deferens, and on 

 the other by the duct of the spermatheca, which is tightly boimd above 

 to the oviduct by connective tissue. I^ear the same spot the retractor 

 muscle of the penis finds an attachment, and the spermatheca and the 

 upper part of its duct are so hidden and so closely applied to the 

 oviduct, that at first sight the lower part of the former appears to be 

 continuous with the latter, and thus to be vagina, while the swelling 

 of the oviduct might well be a spermatheca. The vas deferens, again, 

 is firmly bound for a considerable part of its length to the penis, which 

 it enters at its junction with the retractor muscle. 



The radula has been figured by Pilsbry,^ and calls for no comment. 

 The jaw is smooth, as in B. Alexandri, but scarcely separable from the 

 part of the buccal mass to which it is attached, being apparently little 

 more than a hardening of the tissue which forms the upper boundary 

 of the mouth. It was found to be impossible in the three or four 

 specimens investigated to detach the jaw without breaking it into 

 pieces. 



1 T.c, p. 91, pi. xxiv, fig. 10. 



* T.c, p. 87, pi. X, fig. 7. 

 ^ T.c, pi. xviii, figs, o, 4. 



* Man. Couch., ser. ii, vol. ix, p. 172, Frontispiece, fig. 3. 

 5 T.c, pi. li, fig. 3. 



