Dentition of Pulmonale Mollusks. 117 



which the median is pointed, often bifid. There is much variety in the 

 shape and denticnlation of the cusps. The middle denticle is always the 

 smallest. Teeth aculeate when seen in profile. 



By its jaw, Gceotis calls to our mind the genua Amphibulima, 

 and many species of Bulimulus and Cylindrella. There is some 

 resemblance in its lingual dentition to the marginal teeth of 

 Orthalicus and Liguus, as well as of Polymita muscarum. It 

 also forcibly reminds one of some of the features of the denti- 

 tion of Triboniophonts. 



Amphibulima. 



Amphibulima patula, Brug. Dominica. St. Kitts. 



Jaw (PI. XV, fig. E) slightly arcuate, low, ends attenuated: extremely 

 thin and transparent, with prominent transverse stria?, divided longitudi- 

 nally by about forty -five delicate ribs into so many plate-like sections of the 

 same character as those of Cylindrella, Macroceramus, and many species of 

 Bulimulus. No upper triangular median plates as in Cylindrella. Margin 

 serrated by extremities of ribs. 



Lingual membrane (PI. XIII, tigs. C, D) from a specimen from Dominica, 

 long and broad, composed of numerous horizontally-waving rows of teeth, 

 of the form usual in the Helicidce. Centrals with subquadrate base of attach- 

 ment extended at basal angles, narrowing towards the centre, expanding 

 towards the upper edge, which is reflected and tricuspid, extending quite to 

 the base of the tooth; the cusps are stout, the median one bluntly pointed, 

 each bearing a cutting point. The lateral teeth are of the same type as the 

 centrals, but asymmetrical. The marginals are long and narrow, rounded 

 at base, narrowed at apex, reflected and bicuspid; cusps short, stout, bear- 

 ing a cutting point, and generally a simple modification of those of the 

 laterals. The extreme marginals have irregular cutting points, like simple 

 papilla?. Fig. D shows a group of laterals. Fig. C shows the changes from 

 centrals to extreme marginals. 



PI. XIII, fig. A, shows the dentition of the St. Kitts form, fig. B giving 

 a group of laterals. 



Lately the question of identity of these shells with the Guadeloupe patula 

 has been raised (see Journal de Conchyliologie, XXI, 12). I have, there- 

 fore, again carefulty examined the lingual membranes previously described, 

 to learn if they give any difference worthy to be considered of specific- 

 value. I have figured teeth from each lingual membrane. I regret not 

 having had the opportunity of examining Guadeloupe specimens also, but 

 have never been able to receive the latter with the animal ; indeed it seems 



