282 



TROCEKDINGS OF THE MALACOLOGICAL SOCIETY. 



basal side ; the laterals arc elongate, curved with a slight notch 

 some way below the point (Fig. \e). 



Genital organs (Fig. li). — There is no araatorial organ corresponding 

 to the dart sac. The male organ has a short, free flagellum near the 

 junction of tlie vas deferens, and close to tliis the retractor muscle is 

 given off ; thence the sheath is tubular, widening out below consider- 

 ably, the vas deferens being laid up against it for the whole distance, 

 close to the base ; this is suddenly thickened into a round white sac 

 or diverticulum (the kale sac of Semper), the economy of which it is 

 difficult to imagine; it thence continues as a thin cord to the ovotestes. 

 The spermatheca is very long, wide, and ample at the posterior end. 

 The albumen gland, and all above, had been lost in extracting the 

 animal from the shell. Very interesting was it to find the spermato- 

 phore in the spermatheca (Fig. \c). It consists of a very long, slender 

 tube, given off from a knob-shaped sac. It is quite smooth on the 

 sides throughout, the usual serrations or spines being absent. In the 

 second specimen examined the male organ was the same as shown by 

 Semper (Fig. \d), with an accessory gland. 



The very elongate, large size of the overhanging lobe above tlio 

 raucous pore, quite tail-like in form, recalled at once Semper' s genus 

 Macroceras, from Cebu, Lcyte, and Samar, of which he gives drawings 

 both of the animal and of different parts : this work of Semper's is 

 excellent, and invaluable for investigations of this kind. It is 

 interesting to find an African species presenting a similar development 

 of the foot, but still more so to fincl that here similitude ends. If 

 we looked no further, the two species would be considered congeneric. 

 The internal organs, however, are quite different, and the two forms 

 are widely separated — Macroceras has a straight-edged jaw, with very 

 peculiar, bluntly pointed, simple dentition; an amatorial organ is. 

 present, and there are besides other differences in the genital system. 



I now proceed to notice the following genera, and some of the 

 species included in them by different authors — 



Type not indicated. 

 Type: H. trochifonnis, Fer. 

 Type not indicated. 

 Type : Metcalfei, Pfr. 



Types : plmorMs, Less. ^ ^„ .^^^^^^^^^ 



acutiniurgo, 1 Ir. J 



Type: IT. mijrilcUa, I'fr. 



Tyjie: II. castra, Bens., Ann. & Jlag. 



Nat. Hist. 



II. Moiamhicoisis, Pfr. 



II. Schmeltziaria, Monss , 'Mai. 



Blatt., p. ms. 

 II. cyathellus, 1'1'r. 

 M. radiolaia, V. Mts. 



Tahiti. 



Borneo and 

 I'liilipjiines. 



New Guinea. 



Borneo. 



Negros, I'hi- 

 lipi)iucs. 



iManpicsas, 

 Society Is. 



E. India. 



East Africa. 



Upolo. 



Luzon. 

 Ea.st Africa. 



