WATSON : AFFINITIES OF PYRAMIDULA, ETC. 11 



been published about the excretory system of Pyramidula, Patulastra, 

 and Acanthinula,^ it bas been known for thirty years that the 

 ureter in Vallonia was of a different type from that of Helix,^ although 

 the systematic importance of this difference was at first not generally 

 realized. 



Evidence op the Digestive Syste^t. — The jaw in Pyramidula, 

 Patulastra, Acanthinula, and Vallonia is rather commonplace 

 (pi. I, figs. 5 and 6).* It is thin — extremely so in Pyramidula 

 rupestris — sometimes with a shght median projection, and crossed 

 by a variable number of weak inconspicuous folds. It is usually 

 furnished with a faint, ill-defined, backward extension, more or 

 less divided into a number of small polygonal areas. Precisely 

 the same type of jaw is found in the Pupillidse, Enidae, CochlicopidsBj 

 and some other Orthurethra, but as jaws of a similar kind are also 

 commonly found in various sigmurethrous families, such as the 

 Endodontidae, Clausiliidse, and Achatinidse, not much importance 

 can be attached to the evidence of this organ. 



The radulae of these genera are much more interesting. The 

 Rev. E. W. Bowell has already published in these Proceedings 

 figures of the radulae of Acanthinula aculeata and A. lamellata, of 

 Vallonia costata and V. excentrica, and of Pyramidula rupestris, 

 as well as of Goniodiscus rotundatus and Punctum pygmceum} I am 

 therefore only portraying the radulse of Vallonia pidchella and 

 Patulastra halmei, the embryonic radulae of the last species and 

 Pyramidula rupestris, and the radula of Helicodiscus lineatus for 

 comparison (text-figs. ia-e). 



The following are typical radular formulae of the species with 

 which this paper specially deals : — 



Pyramidula rupestris 

 Acanthinula lamellata 

 Acanthinula aculeata 

 Vallonia costata 

 Vallonia pulchella . 

 Vallonia excentrica 

 Patulastra halmei . 



(11 + 6 + 1 -t- 6 + 10) X 145, 



(8 + 7 + 1 + 7 + 

 (8 + 6 + 1+6 + 

 (9 + 5 + 1 + 5 + 

 (9 + 4 + 1 + 4 + 

 (9 + 4 + 1 + 4 + 

 (17 + 9 + 1 + 9 + 17) X 125 



1 Hesse, however, quotes a brief but important note by Wiegmann, in 

 which it is stated that Pyramidula rupestris has a remarkably elongated kidney, 

 very different from that of Goniodiscus rotundatus or G. ruderatus, but 

 resembling that of Acanthinula aculeata. (Nachr. Deutsch. Malak. Gesell., 

 vol. xlvii, 1915, p. 57.) 



^ Behme, Archiv fur Naturgeschichte, vol. i, 1889, pp. 5, 6. 



' Further figures of the jaw of Vallonia will be found in Sterki, Proc. 

 Acad. Nat. Sci. Phila., 1893, pi. viii, figs. H, I, K, L, M, N, 0, R; of Acanthinula 

 in Lehmann, Die lebenden Schnecken u. Muscheln dtr Umgegend Stettins u. 

 in Pommern, 1873, pi. x, fig. 25, pi. xi, fig. 32 ; and of Pyramidula rupestris 

 in Taylor, Monogr. L. <Ss F.W. Moll. Brit. Is., vol. iii, 1909, p. 171, fig. 226 

 (fig. 227 on the same page evidently represents the radula of a very different 

 species). 



* Proc. Malac. Soc. Lond., vol. xi, 1914, pp. 158-61. Bowell has also figured 

 the radula of Pyramidula rupestris in the Journal of Conchology, vol. xiv, 

 1915, p. 290. 



