42 rUOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



becoming suddenly narrower to form the vas deferens, which also 

 bears in its proximal portion some glandular swellings. The short 

 retractor penis originates in the diaphragm, and lias its distal insertion 

 at the junction of the vas deferens with the long penis. The latter 

 consists of a narrow spiral portion and a wider distal one : a true 

 epiphallus camiot, however, be distinguished. Probably the sperm 

 is not enclosed in a spermatophore, but freely ejected. The upper 

 part of the pale-yellowish oviduct is wide and glandular ; the distal 

 ])ortion is narrow and cylindrical : after uniting with the duct of the 

 elliptical receptaculum seminis it forms a long vagina. A common 

 atrium gcnitale is barely distinguishable. The receptaculum contained 

 only mucous matter, and no traces of spermatophores : this accords 

 with the structure of the penis. The inner walls of the penis and 

 vagina are lined with papillae. Those of the latter ai'e cartilaginous, 

 and disposed in rows of six, and higher up of five, presenting the 

 appearance of a head of maize (PI. V, Fig. 10). Those of the penis 

 are stout and conical in shape, and vary somewhat in size (PI. V, 

 Fig. 11). The suggestion may be hazarded that during copulation 

 the papillae of the penis {Hcizjjcqjilkn) interlock with those of the 

 vagina. 



The nervous system. — The most significant point about the nerve- 

 collar is the shortening of the visceral commissure. The cerebral ganglia 

 are connected by a long commissure, equalling in length the maximum 

 diameter of a single cerebral ganglion. The arrangement of the buccal 

 ganglia is precisely similar. The lateral connectives are, however, 

 shorter than the cerebral commissui'e. The pedal ganglia are united 

 as in all Stylommatophora ; the pleuro-visceral ganglia, welded into 

 a single transverse mass, lie immediately above them. This mass is 

 narrower in the middle than it is towards the sides. The union of 

 the ganglia appears to be very intimate, since there is apparently only 

 a feeble connective-tissue sheath. The origin of the nerves I have 

 not been able to trace out. 



The muscular system and tentacles. — The degree of development 

 of the tentacles seems highly interesting, since I can distinguish only 

 two, i.e. the ommatophores, the lesser pair being wanting. Possibly 

 a small knob on the left side might be interpreted as representing one ; 

 but since I found no corresponding one on the right side, this knob 

 was probably a projection of the pedal gland, or a lobe of Semper's 

 organ, or a mesenterial thickening. Indeed, the various delicate 

 structures around the mouth are difiicult to distinguish. I think it 

 is certain that the smaller tentacles, if not wanting altogether, are 

 yet more reduced than in Succinea. The right ommatophore 

 embraces the penis on the outer side, as in Helix. The columellar 

 muscle resembles in a certain sense that of TTrocychis or Parmacella, 

 but a more careful investigation reveals some distinctive differences. 

 The short, common stem originates on the right side of the posterior 

 margin of the mantle-line. There is some reason for the suggestion 

 that this point originally coincided with the nucleus of the shell 

 and the yellow spot on the mantle above described, a divergence 

 taking place during growth. Further on, the muscle splits up into 



