282 FAUNA HAWAIIENSIS 



must be noted that the median teeth have a single outer cusp, while Kaliella has both 

 outer and inner cusps ; this latter characteristic is, however, not present in Sitala. 

 Kaliella has few teeth in the row, Sitala many ; 33 : i : 33. 153 : i : 153, respectively. 

 A more important link with the genus Sitala is displayed by the presence of right and 

 left shell lobes, which Kaliella does not possess ; the close parallel lines of contraction 

 across the right shell lobe shew that it has considerable extension in life. Stoliczka 

 also mentions in Sitala infiila the swollen uterus and the advanced state of development 

 of the ova ; pointing to similar embryonic stages in these molluscs. Yet another 

 character is in common, namely, the absence of any amatorial organ. The male organ 

 of the present species is also slightly different ; I am unable, having only one specimen 

 to dissect, to e.xamine this in section. 



" The jaw is very thin and delicate, and so colourless that its detection and ex- 

 traction are very difficult. It has a well defined central projection on the cutting edge. 



" The generative organs (Plate XII. figs. 3, ^a) cannot be described so fully as one 

 would wish, owing to the expanded state of the uterus. The hermaphrodite duct and 

 albumen gland were perfect : and the male portion thence complete. The prostate — as 

 it is called by Semper, shewn in his figure of Microcystis myops as a loose fringe-like set 

 of convolutions — appears in this species as a closely packed and thickened mass of 

 oblong form, flattened on one side, where the oviduct would be lying attached if perfect. 

 The vas deferens is given off at the anterior end. The penis is a thickened muscular 

 tube, broad and bulbous below, tapering upwards to where the very short thickened 

 retractor muscle is given off: the vas deferens at this point has three sharp con- 

 volutions ; seen with transmitted light a short, sharp, ' kink ' occurs in the bulbous 

 portion near the generative aperture. 



" The sculpture of the shell, magnified about thirty times, presents a very fine, 

 regular, slightly wavy, longitudinally striated surface ; this striation is strongest near 

 the suture, becoming finer outwards. There are about i i striae to -003 inch. The 

 most advanced embryonic shell consists of 2^ whorls, the sculpture is well shewn on it. 



" The point now to be solved is whether we are to retain this species in Microcystis. 

 Mr Sykes regards' M. orjiatella as the type of the genus ; this was also the opinion of 

 H. Nevill. Further Mr Sykes goes on to say ' Now these small Zonitoids \i.c. those 

 of the Hawaiian Islandsl hardly fit into the same genus as this species and therefore 

 some other generic title is required for them.' The anatomy now described, shews, for 

 many reasons, that the shell cannot be placed in Alacrochlamys as Mr Sykes, guided by 

 the shell characters, proposed. In my opinion it is undoubtedly close to Kaliella, 

 still closer to Sitala, and yet there are sufficient differences in the generative organs to 

 separate this Hawaiian form from both. If we take the shell alone into account, the 

 sculpture presents one character, viz. fine, close longitudinal striation, not found in the 

 Indian species of Sitala, in which the general surface is smooth, with spiral liration. 



' P. Malac. Soc. London, 11. 1896, p 131. 



