Say on Shells, &e. : 44 
Species. 
1. B, ovata, elongated ; transverse septa subovate, sixlo- 
bed and a smaller one behind ; lobes of the superior faces of 
the septa, three on each side, with a minute one between 
each, dentated at their edges, anterior lobe, (nearest the 
siphuncle) small not sinuous, second lobe with a single pro- 
jection each side and sinus at tip, third lobe dilated, with a 
small sinus each side and more obtuse and profound one at 
tip, posterior lobe hardly larger than the lateral intermedi- 
ate ones. 
Greatest diameter of the transverse section one inch and 
one fifth, smaller diameter seven tenths; length of the seg- 
ment about half an inch. 
The specimen is in the collection of Mr. Reuben Haines 
of this city, it was found on the Neversink hills, in Mon- 
mouth County, New-Jersey, it is a cast of three very entire 
segments, no vestige of the shell remaining. ‘The dimen- 
sions are taken from the largest segment. 
In point of form this species approaches B. nerhebini dig 
am. particularly in the curvature of the transverse section, 
but it is somewhat more obtuse behind ; another difference 
consists in the form of the lobes, which, in that species, as 
represented by Mr. Desmarest, are less symmetrical, des- 
titute of the lateral processes and of the profound terminal 
sinus ; that species also. is very diminutive. 
2. B, compressa, elongated, much compressed ; transverse 
septa oblong-oval narrowed to each end; odes dilated, 
dentated on their edges, each with from three to five si- 
nuses each side and a very profound one at tip. 
This description is taken from two fragments in the col- 
lection of the Academy of Natural Sciences, which were 
brought from the Missouri, one by Messrs. Lewis and Clark 
and the other by Mr. Thomas Nuttall. As they exhibit the 
appearance of having been violently compressed by fortu- 
itous circumstances, I have not been able to obtain correct 
proportional dimensions of the species. But notwithstand- 
ing this distortion of form, I have much confidence in placing 
it next in specific affinity to B. Knorriana, Desm. as it has 
without doubt been naturally a much compressed shell, with 
the lateral edges not very unlike those of that large and re- 
Vor. Ii.....No. 1. 6 
