GODWIN-AUSTEN : ON THE GENUS EURYSTOMA. 49 



right dorsal lobe is large, the left very small. The pulmonary cavity 

 is not very capacious. The renal organ (Fig. 6) is elongate, with an 

 even width, the heart being situated at the posterior end. 



The generative organs (Figs. 9-11) are very simple, there being 

 neither dart- sac nor digitate glands, and no caecum to the spermatheca 

 duct. The albumen gland is remarkably large. The spermatheca is 

 a long narrow duct with a pear-shaped swelling at the distal end. The 

 penis has a short flagellum, at the base of which the vas deferens is 

 attached. There is a bulbous swelling or knob, below which the 

 retractor muscle is attached, and this muscle, spreading over the 

 sheath, gives rise to another strong retractor, having its attachment 

 on the body- wall near the reproductive aperture. 



The jaw (Fig. 5) has six well-marked folds and an indistinct one on 

 each outer side, thus eight in all. 



In the radula (Figs. 4, 8) the formula is 34-16-1-16-34 or 50-1-50. 

 The central teeth are broad, not very pointed, with no side cusps, only 

 a slight emargination, the merest indication of them ; at about the 

 22nd median tooth a small lateral ectocone makes its appearance ; in 

 the outer teeth, about the 36th, both mesocone and ectocone become 

 bicuspid on a more elongate oblong plate, thence the plates become 

 narrower and narrower towards the extreme margin with irregular 

 denticles here and there, showing only a trace of the form of the 

 35th tooth. 



As might be expected, this genus of the Helicidae differs widely 

 from European genera represented by Pomatia {pomatia), Tachea 

 (nemoralis), Euparypha (typical Pisana and desertorum), Arianta 

 (arbustorum), etc. I have not sufficiently gone into the anatomy of 

 the genera of Helicidae to make any useful comparison, and many 

 Indian species remain to be examined before changes are made in 

 classification. 



Ferdinand Stoliczka made perhaps the first dissections of Indian 

 Helicidae. In the Journal of the Asiatic Society of Bengal, 1871, 

 pp. 223-228, he described the genus Trachia, of which the type is 

 asperella, Pfr., from Bengal. The species described by Stoliczka is 

 delibrata, a species with a wide range in eastern India. PI. xvi, 

 figs. 1-3 show that the genitalia are of the same simple type, with 

 no glands, appendages, or dart-sac present. The jaw especially and 

 radula, however, differ, but not materially. In 1873, in the same 

 journal, pp. 24-26, Stoliczka described Trachia Penangensis. In this 

 species we find the generative organs approach nearer to those of 

 JE. vitfata, especially in the form of the spermatheca. The jaw is also 

 similar in having fewer ribs, and the radula is evidently of the same 

 type, but the teeth are on narrower plates and more pointed. As far 

 as the animals are concerned, Eurystuma and Trachia with Planispira 

 (vide H. aryillacea, Fer., from Timor: Semper, pi. xv, fig. 19) come 

 near each other. On the other hand, their shells differ very much in 

 form, and particularly in type of sculpture. In this instance it is 

 unfortunate that Stoliczka says nothing about the sole of the foot in 

 his description of the animals of Trachia which he dissected, and 

 from this I infer thei'e was nothing remarkable to note. The divided 



VOL. VI. — MARCH, 1904. 4 



