30 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY, 



differ widely in their anatomy from the Endodontidae, Helicidse, and 

 other sigmurethrous families, but they have much in common, not 

 only with the Pupillidse, but also with the Cochlicopidae, the 

 Amastridse, and at least the Palsearctic division of the Enidae. The 

 latter groups, however, seem to differ so slightly from one another 

 and from the Pupillidae, that they also might well be included in 

 that ancient family, which appears to be divisible into a large 

 number of inter-related sub-families, comprising much diversity in 

 the shape of the shell. 



The three British forms of Vallonia are distinct, though nearly 

 allied, species ; they should be placed in the following order : 

 1, F. costata; 2, V. pulchella; 3, V . excentrica. The two British 

 species of Acanthinula belong to separate sub-genera. 



EXPLANATION OF PLATES. 

 Fig. Plate I. 



L Vallonia excentrica Sterki, from Oakamoor North Staffordshire, Avithout 

 its shell, seen from below. x 25. a.l., anterior division of liver; 

 al.g., albumen gland; aur., auricle; i7it., intestine; kid., kidney ; 

 m.c, mantle-cavity ; ce.9., oesphagus ; p. a., posterior aorta ; p.l., 

 posterior division of liver ; r.m., retractor muscles ; s.gl., salivary 

 glands ; sL, stomach ; ur., ureter ; ut., uterus ; vnt., ventricle. 



2. Reproductive organs of Patulastra balmei (P. & M.), from Glasnevin 



Botanic Gardens, Dublin, x 8. 



3. Penis (cut open) and anterior part of epiphallus of P. balmei. x 22 5. 



4. Head and anterior part of tail of spermatozoon of P. balmei. x 1200. 



(The entire spermatozoon is about J mm. long, only about one- fourteenth 

 of the tail being shown in the figure.) 



5. Jaw of P. balmei. x 30. 



6. Jaw of Vallonia excentrica. x 100. 



Fig. Plate II. 



1. Head and anterior part of tail of spermatozoon of Pyramidula riipestris 



(Drap.). X 1200. 



2. Head and anterior part of tail of spermatozoon of Vallonia costata (Miill.). 



X 1200. V. excentrica has very similar spermatozoa. 



3. Pyramidula rupestris (Drap.), from Burnsall, Wharf edale, without its 



shell and with its head retracted, seen from above. x 22. a.l., 

 anterior division of liver ; al.g., albumen gland ; ft., foot ; g.u., groove 

 running backwards from opening of ureter ; int., intestine ; kid., 

 kidney ; p. a., upper branch of posterior aorta, thickly coated with 

 a calcareous deposit ; p.l., posterior division of liver ; ret., rectum ; 

 r.m., retractor muscles ; r.o., respiratory orifice ; r.s., receptaculum 

 seminis ; st., stomach ; ur., ureter. 



4. Reproductive organs of Pyramidula rupestris (Drap.), from Burnsall, 



Wharfedale. x about 22. 



5. Reproductive organs of a specimen of Vallonia costata (Miill.), from Little 



Shelford, Cambridgeshire, with a penis and two penial appendices. 

 X about 25. 



6. Reproductive organs of Vallonia pulchella (Miill.), from Madingley, 



Cambridgeshire. x about 25. 



7. Head of spermatozoon of Acanthinula lamellata (Jeff.). x 1200. 



8. Head of spermatozoon of Acanthinula aculeata (Miill.). x 1200. 



