176 Review of Geinitz on the rocks and fossils of Nebraska. 
Woodward, Carpenter, Gray, H. & A. Adams, Deshayes, pee 
in short, all good conchologists admit this as a distinct genus 
from Nuc ula; while Carpenter, H. & A. Adams, MGrch, and other 
late systematic writers, separate it as the type of a distinet joa 
from the Nuculide. 
But the most unaccountable error into which Prof. Geinits 
has fallen, is in placing in the genus Rhynchonella, Spirifer heme 
— of — — type of the new genus Syntrilasma, Meek 
& Worth n (Ll. G eol. Report, ii, 821). Being a somewhat 
peculiar shell, if the cardinal region of the valves was hidden 
in the matrix, "and the oer ~e somewhat obscured, it — 
by a triangular open fissure, while another re shows it to 
have in the dorsal valve, the crura and cardinal process, a8 iM 
Orthis. The fact is, this shell does not even belong to the Rhyn- 
chonellide, as its punctate structure and other characters show. 
The fact that Prof Geinitz, after referring it to Rhynchonella, 
speaks of it as “this rare and beautiful Terebratula,” would also 
seem a indicate that he does not even regard the distinctions 
tween these two —_ arse known to be the types of two 
Rescues families), of much consequence. 
Again Prof. Geinitz ubcainbles important distinguishing char- 
cters, when he refers (without even a recognition sub- 
genus) to the genus Orthis, a typical Streptorhynchus (properly 
onites). The distinctions between these types are well 
Salas; so much so that even Mr. Davidson, who is comps cau- 
tious: -and conservative in fe even subgene consi 
the spines figured by Prof. Geinitz 
tin te “ea 29), 2 8 peice by him to Actinocrinus, as those of 
nus mucrospinus McChesney. These spines, probably 
longing to two or more allied species, are widely distributed in 
our ee from West Virginia and Pennsylvania, ® e = 
reely necessary to explain here that when Prot de Konink seat ’ 
ibing A nchonella pear Linn (to which species Prof. Geivitt 
nder consideration), he alludes to ole sevih oval mond on each 
0 dhe beaks at an angle of about nine 
Ii any one, however, has re Bacio “ 
one, t 
Feme be oi parte tee pe 
ata |. ‘. —_ after a careful of Liane 
lo s. Carb, : — a study of . 
ele eee 
