84 Dentition of Pulmonate Mollusks. - 



Urocyc*Iu§. 



Urocyclus KirJcii, Gray. Mozambique. Mr. J. 8. Gibbons. 



Jaw (pi. XVI, fig. K) very low, slightly arcuate; ends scarcely attenuated, 

 blunt; anterior surface without ribs; no median projection to the cutting- 

 edge; a strong muscular attachment. 



Lingual membrane (pi. XVII, tig. N)with tricuspid centrals, bicuspid lat- 

 erals, as in Zon'des, and aculeate%iarginals, all of which are bifid. 



The figure shows one central, one lateral, and two marginals. 



Nanina. 



The species of this genus have tricuspid centrals, bicuspid 

 laterals, and bifid aculeate marginals. I have examined from 

 Mauritius (Consul Pike), — 



Nanina Oaldwelli, Benson. 



X Raiusonis, Barclay. (PI. II, fig. D.) 



X. argentea, Rve. (PI. II, fig. 0.) 



X. implicata, Nev. (PI. II, fig. B.) 



X. stylodon, Pfr. 



The last cannot be retained in Erepta, a sub-genus of Helix, 

 where it was placed by Von Martens. All the above have similar 

 dentition. Also from Mauritius — 



N. philyrina, Morelet. 



Though this species agrees in other respects with the above-named, the mem- 

 brane is very broad, the teeth exceedingly numerous, arranged in oblique 

 rows. The centrals, which I am confident of having seen, are small, narrow, 

 high. The other teeth are the same in form to the edge of the membrane. 

 They appear to have the usual aculeate form of the marginal teeth in Nartina; 

 but instead of narrowing towards the cutting-point, they are broadly and 

 obliquely truncated, reflected, and minutely denticulated. This lingual mem- 

 brane is also figured by Semper (Phil. Archip., pi. VI, f. 35); but his figures 

 give more the impression of the usual Nanina marginals with denticulated 

 side and bifid points. The teeth are, however, so exceedingly numerous 

 and small that it is very difficult to understand them. 



Nanina inversicolor, Fer. 



Also from Mauritius, has the character of animal, jaw, and lingual mem- 

 brane of Nanina, so that it cannot be retained in Oaracolus, a sub-genus of 

 Helix. 



Nanina militaris, 



Of same locality, for the same reasons cannot be retained in Stylodon, and — 



