354 THE DEVONIAN FOSSILS OF CANADA WEST. 
History of the Genus. 
The somewhat numerous species which belong to this genus, have 
been variously distributed and shifted about among the genera 
Ambonychia, Cardiomorpha, Edmondia, Modiola, Modiolopsis, Megam- 
bonia, Palearca, Cypricardinia, Megalomus, and Cypricardites in a 
very remarkable manner. Conrad, the first Paleeontologist of the 
New York Survey, placed all the species, (twenty-three in number) 
described by him in a single genus, and I think that the many changes 
made by his successor in office, have not been productive of any 
improvement on that simple arrangement. The following are a few 
of the facts : 
In the fifth Annual Report on the Paleontology of New York, 
Conrad, in 1841, characterized his genus Cypricardites and described 
sixteen species from the Silurian and Devonian rocks of the State. 
He did not give any illustrations, but it now appears that he prepared 
a figure, (shewing the characters of the hinge,) which, however, 
remained in Professor Hall’s hands eighteen years without publication. 
In the 8th volume of the Journal of the Academy of Natural Sciences, 
Conrad described seven other species from the Devonian rocks of New 
York. These are all figured. 
In 1847, Professor Hall suppressed the genus Cypricardites and 
substituted his own genus Modiolopsis, in which he placed all Con- 
rad’s Lower Silurian species. The following are his remarks in a 
note at the foot of p. 157, Vol. 1. Pal. N. Y. 
“T find myself compelled to abandon the use of the name Cypricardites, as 
applied to shells differing so widely as these do from Cypricarpia, and belonging 
apparently to the Monomyaria and Dimyania. So faras itis possible to ascertain, 
none of the species of the older strata possess two muscular impressions, and 
therefore do not strictly fall under the genus Cypricardites of Conrap, (Ann. 
Geol. Report, 1841, p. 51:)” 
The principle upon which the above decision was given, is perfectly 
correct. It is one of the established laws of nomenclature that a 
name which involves a zoological error (such as referring a genus to 
the wrong place in the system of classification) should be excluded. 
The reasons given by Protessor Hall for bringing Cypricardites 
within the operation of this law are not so well founded, because both 
Modiolopsis and Cypricardites have two muscular impressions. The 
correct reason is that the name implies a close relationship to the 
recent genus Cypricardia, which belong to the family Cyprinip& 
