512 ON THE AUSTRALASIAN GUNDLACHIA, 



I res^ret that I can give but a meagre account of the soft parts. 

 My only material was some specimens procured at Adelaide, 

 which died on the voyage to Sydney and were hastily and badly 

 preserved on board the steamer. 



The external appearance of spirit specimens is conveyed by 

 tigs. 7 and 8. Part of tlie liver and the hermaphrodite gland are 

 pinched off into a sort of tail, which occupies the primary shell. 

 With this exception, as Gundlach and other observers have 

 remarked, there is no difference from Ancylus. The form and 

 disposal of the stomach and intestines seemed, as well as I could 

 ascertain, to agree with those of A7icylus figured by Moquin-Tandon. 



Jaw (fig. 9) extremely minute and frail, about f the length of 

 the radula, very narrow, composed of a great number of separate 

 imbricating plates (fig, 10), which appear to be arranged two deep, 

 in contact but unattached, each is oblong in shape and serrate at 

 one end, resembling somewhat the scales on some butterflies' 

 wings. 



The difficulty of observing this tender and incoherent organ will 

 account for the uncertainty that prevails regarding it. Troschel 

 saw it, described it, and then unfortunately concluded that it was 

 a piece of hardened skin. Stimpson failed to find it. Johnston 

 noticed it in G. petterdi. In Latia Hutton asserts (Trans. N.Z. 

 Inst. xiv. p. 156) that no jaw exists ; it has more probably been 

 overlooked. 



Radula (fig. 11) a narrow parallelogram, very small, measuring 

 about 3 X 1 hundredths of an inch. Formula, 70 rows of 

 8 : 12 : 1 : 12 : 8. Each half row straight, meeting at a low 

 angle in the centre. Rachidian with a long slender basal plate, 

 rounded and slightly expanded ])osteriorly ; reflection about a fifth 

 of total length, bicuspid. Laterals with broad basal plates, emar- 

 ginate at the proximal posterior corner, sloping aw^ay from the 

 rachidian, reflection somewhat pyriform, the wide end proximal, 

 set aslant on the basal plate and armed with a large proximal and 

 two minor distal cusps. Marginals more upright, with reflection 

 of same pattern, but extending almost the length of the basal 

 plate. 



