NATURAL SCIENCES OF PHILADELPHIA. 183 
and bears a short, stout, median cusp, having a short, blunt, 
cutting point. There are no side cusps or cutting points. 
The laterals } are like the centrals, but unsymmetrical; their 
reflected portion is also longer. The outer laterals (e) have an 
outer side cusp. 3 
The marginals d are a simple modification of the laterals, being 
quadrate, longer than wide, with one inner broad, long, oblique, 
bluntly pointed cutting point, bearing an inner, side, short, acute 
cutting point. These cutting points on the extreme marginals e 
are simply short and bluntly. rounded. 
Some membranes examined by me seemed to have an extension 
to the base of attachment beyond the upper margin of the reflected 
portion, to which it was parallel. 
This membrane is peculiar in the long, narrow base of attach- 
ment and short reflected portion of the central and first lateral 
teeth. 
Genus HOLOSPIRA, Mart. & Alb. 
There are two species of this genus found within our limits, 
H. Goldfusst and Roemeri, the former of which I have been able 
to examine. I have not been able to examine lingual mem- 
brane of H. Remeri, but, thanks to Mr. Bland, I have examined 
and here figure (pl. X.X., fig. 10) that of H. Goldfussi.. There are 
26—1—26 teeth, with about 9 laterals. The cusps of the marginals 
are quite widely separated. The general characters of the teeth are 
as described below. I can refer also to Messrs. Fischer and Crosse - 
for information regarding the jaw and dentition (Journ. de Conch. 
XVIII. 18, 1870, pl. V., and Moll. Mex. et Guat., 320, pl. XVI.) 
The jaw is arcuate, with slighly acuminated, blunt ends, thin, 
anterior surface ribless; cutting edge simple; transversely and 
vertically striated. 
The lingual membrane in H. Tryont and Pfetffert examined 
and figured by those authors, is of the usual Helicine type. The 
centrals and laterals have a single short cusp, bearing a short, 
blunt cutting point, both side cusps and side cutting points being 
absent; marginal teeth quadrate, wide, low, with one long, inner, 
obtuse cutting point, and one outer, side, short, blunt cutting 
point. 
