GODWrjT-ATTSTEN : ANATOMY OF nEMIPLECTA FLOWERT, ETC. 33 



raclula, and shell and dorsal lobes, and I therefore leave it, where 

 Mr. E. A. Smith placed it, in Hemiplecta. 



I' Hemiplecta neptuna, Pfr. 



Specimens of another large land- shell, taken in Siam, exact locality 

 not stated, have lately been received from Mr. Daly. These, thanks 

 to our President, I have examined : with one exception they were not 

 in the best state of preservation. They had been identified as 

 H. distincta, Pfr., but I now believe, for reasons given below, that 

 they are H neptuna, Pfr. 



External Features. — No right shelldobe is present, but there is an 

 indication of a small left shell-lobe (Fig. 12) just above the division 

 of the left dorsal lobe into the usual anterior and posterior parts : 

 it is represented by a slight widening and turning back of the edge 

 for 3 mm. The left dorsal lobes are very narrow for the large size 

 of the shell. At about 12 mm. from the respiratory orifice is the 

 division between these dorsal lobes, 2 mm. wide ; the posterior 

 portion commences and continues as a distinct narrow lobe for 

 1 9 mm. The foot, which appears to have been of a ruddy ochre 

 tint, is streaked and blotched sparingly in one specimen with dark 

 grey ; in the others it was plain. The peripodial margin is nearly 

 3 mm. in width, but the two parallel grooves above it are not 

 conspicuous. The central area of the foot is not defined. The segment- 

 like cross -lines of the peripodium can be followed beneath the edge 

 of the foot, and at a short distance disappear. The mucous pore is 

 broad, triangular in shape, similar to that of Haughtonia conferta, Pfr. 



Internal Anatomy. — Genitalia (Fig. 13). — The amatorial organ is 

 very long, about 45 mm., with a diameter of 4 mm. To its posterior, 

 rounded end is attached a long retractor muscle, unusually broad 

 in one specimen. The male organ (Fig. 13«) agrees in general 

 with that of Hemiplecta Humphrey siana and H. Floiveri, the kalk- 

 sac being small as in those species ; it varies, however, in the portion 

 near the attachment of the retractor muscle. Where the penis bends 

 on itself, a broad muscle lies along the edge, then follow a sharp 

 bend and a short blunt coecuin-like process, from which a long- 

 thin muscle extends : the latter is always present ; but the broad 

 muscle here seems additional. The spermatheca is attached at its 

 usually free end by well-developed muscles to the base of the 

 oviduct; it is short, oval, rather transparent, on a thick, short stem. 

 There is a large globose swelling on the free oviduct, and as it 

 came into view during dissection among the genitalia and other 

 organs of the body it was very conspicuous by its yellow colour. 

 I have suggested that a similar enlargement present in some other 

 genera in this position may be an ovitheca. Its precise function has 

 yet to be discovered, but this may possibly be gleaned by studying 

 sections. 



Radula (Fig. 14). — The central tooth is long and narrow; the 

 admedian teeth are plain, straight-sided, and there are more than 



vol. iv. — march, 1900. 3 



