118 Dentition of Pulmonate Mollusks. 
to be now found subfossil only.* I can only treat the question of the 
identity of the St. Kitts and Dominica forms, not their identity with Guade- 
loupe forms. 
It will be seen that the Dominica form has sharper cutting points to the 
large cusps of its central and lateral teeth than that of St. Kitts. Fig, B 
shows a group of laterals of the former, in which some variation from the 
pointed shape is indeed shown, but no decided tendency that way. On the 
other hand, the laterals, from the St. Kitts form, show great constancy in 
the square truncation of the cutting points. (Fig. B.) 
The teeth of the St. Kitts form are broader in proportion to their length 
than those of Dominica, have a greater curve in their outlines, and more 
developed side cusps, which overlap the median cusps. 
The Dominica lingual in the only row counted had 87-1-87 teeth. A row 
of the St. Kitts form had 57-1-57. The marginal teeth of the St. Kitts form 
show a greater tendency to splitting into sharp denticles on the cutting 
cusps than those of Dominica. | 
It cannot be denied that certain variations may be noticed in the two lin- 
gual membranes. I believe, however, that these differences are not such 
as suggest specific distinction, especially as the shell furnishes no grounds 
for doubting the specific identity of the forms. 
Mr. Bland has given a detailed account of the species in Journal de 
Conchyliologie, X XI, 342, October, 1873. 
Ainphibulima Rawsonis, Bl. Isle of Montserrat, between 
Nevis and Guadeloupe. Goy. Rawson. 
Jaw as in A. rubescens, about 33 ribs; those at the upper centre running 
obliquely and meeting or ending before reaching the lower margin. 
Lingual membrane (P]. XIII, figs. H, G) as usual in the genus. Centrals 
with the base of attachment very much larger than that of the laterals, and 
with an enormous, single, broad, long, rapidly and obtusely pointed cutting 
pomt. No side cusps or side cutting points. Laterals of the form usual 
in the Helicinw, with a stout, inner cusp, bearing a broadly truncated, short 
cutting point, aud a small side cusp bearing a short cutting point. 
The change from laterals to marginals is shown in the 10th, 15th and 
27th teeth in the plate. 
The marginals (28th and 68th teeth in the plate) have a long, narrow base 
of attachment, which near its lower margin bears a short, slightly expand- 
ing, bluntly trifid cusp; from this cusp springs a short, expanding, bluntly 
denticulated, broad, cutting edge, the inner denticle the largest. This cut- 
ting edge is shown in the 67th and 68th teeth on a more enlarged scale, 
There is great variation in the denticulation of the cutting edge. There 
are 68-1-68 teeth. 
* See, also, under A, Rawsonis, for Fischer’s description of the dentition 
of the Guadeloupe form. 
