230 PROCEEDINGS OF THE ACADEMY OF 
full account of its history with all published information relating 
to it has been given by Mr. Bland and myself in Ann. of Lye. Nat. 
Hist. of N. Y., X., 306. The jaw is low, wide, slightly arcuate, 
with blunt, squarely truncated 
ends; it is composed of six- 
teen separate pieces, each 
higher than wide, with slightly 
overlapping edges; these 
Jaw of F. pygmeum. [Morse.] pieces do not run obliquely 
towards the middle of the jaw, 
there is, therefore, no appearance of an upper median triangular 
piece as in Orthalicus and Liguus. 
The lingual membrane is long and narrow. There are 54 rows 
of 13—1—13 teeth each. The centrals have a base of attachment 
much longer than wide, expanded 
Fig. 70. below and squarely truncated, very 
Nae : much narrowed above, reflected. 
The reflection is very small and has, 
according to Morse, one single cusp, 
but Schacko (Malak. Blatt. 1872, 
Subba ES 178) describes the reflection in some 
Ee, iar “pygmeun. — Wuropean specimens as_ tricuspid. 
Laterals of same form as centrals, 
but with wider base of attachment in the first ones and bicuspid ; 
outer laterals much narrower. There are no distinct marginals.’ 
All the teeth are decidedly separated. 
I have not examined the jaw or lingual membrane of this spe- 
cies, but am entirely dependent on Morse for the descriptions and 
figures of the American form given above. While treating of the 
identity of the American and European forms in the paper refer- 
red to above, we have pointed out the differences in the jaw and 
membrane of the two forms, which, however, do not appear to be 
of specific value. . 
d. Jaw ina single piece, with an accessory, quadrate plate above. Mar- 
ginal teeth quadrate. SuccrnIné. 
Genus SUCCINEA, Drap. 
Jaw with an upper, quadrangular, accessory plate. The jaw is 
strongly arched, the ends acuminated in S. avara (fig. 71), blunt 
