Dentition of Pulmonale Mollushs. 119 



The peculiarity of this membrane is the enormous development of the 

 central tooth. 



Fig. G shows a lateral in profile : I have given figures of the dentition of 

 A. patula, Brug., of St. Kitts and of Dominica, of A. appendiculata, Pfr., of 

 Guadeloupe, and of A. rubescens, Fer., of Martinique. Dr. Fischer (Journ. 

 de Conch., XXII, 1874, PI. V) figures that of A. depressa of Guadeloupe. 

 and .1. patula of Guadeloupe. 



Dr. Fischer also (1. c.) figures the dentition of A. rubescens. He gives 

 inner side cutting points to the lateral teeth, which I did not find in my 

 specimens. His figure of the dentition of the Guadeloupe A. patula is cer- 

 tainly specificalty distinct from the St. Kitts and Dominica form. It seems 

 as if there were the following distinct species of Amphibulima: dqwessa, ap- 

 pendiculata, rubescens , patula of Guadeloupe, patula of St. Kitts and Dominica, 

 and Raicsonis. 



Amphibulima rubescens, Desh. Martinique. Gov. Rawson. 



The jaw is readily detached from the muscles of the mouth, and is not 

 connected with the lingual membrane as usual with, our Helices .* It is 

 thin, wide, low, arched, with attenuated, bluntly pointed ends, divided by 

 numerous (about 63) delicate ribs into separate plate-like divisions, as in 

 the jaw of Cylindrella. BuUmulus, etc., the ribs running somewhat obliquely 

 towards the centre of the jaw; there is no decided, upper median, triangular 

 plate. (PI. XV, fig. D.) The lingual membrane (PI. XIII, fig. F) is long, 

 broad, composed of numerous row T s of 76-1-76 teeth. Centrals long, narrow, 

 expanding below, with the lower margin of the base of attachment squarely 

 excavated as in Succinea ; tricuspid, the central cusp very long, wide, with a 

 greatly expanded, squarely truncated cutting point reaching beyond the lower 

 margin of the base of attachment ; the side cusps short and narrow, simply 

 pointed. The lateral teeth are of same type as the centrals, but asym- 

 metrical and bicuspid. The marginals are a simple modification of the 

 laterals, with a long, bluntly truncated median cusp, and obsolete side cusps. 

 The extreme marginals are irregularly denticulated, the outer and inner 

 denticles being more produced, especially the outer, and greatly curved ; 

 the inner denticles, usually two in number, are quite small. 



Amphibulima appendiculata, Pfr. Guadeloupe. Gov. Rawson. 



Jaw (PI. XV, fig. F) extremely thin and transparent, long, low, slightly ar- 

 cuate, ends blunt, divided longitudinally by about 40 regular ribs into as many 



* Even after boiling the whole buccal mass in potash, the lingual mem- 

 brane and jaw remain attached in most of our Helices of N. A. showing a 

 decided connection between the two. 



See last species for remarks on Dr. Fischer's description and figure of 

 the dentition of the species. 



