48 °C Barrois—Review of Professor Hall's recent volume 
Chemung. It is interesting to note the complete absence of 
the allied genus Bucania, which, on the contrary, is so widely 
distributed in the Silurian of this region. 
There are, however, certain genera of Gasteropoda, which 
appear peculiar to the Devonian formation of America. Suc 
are the Cyrtolites of Conrad (two species), and the C 
(six species)—a new genus of Mr. Hall analogous to Pleuroto- 
maria. The Callonema, another new genus (three species) in 
which Mr. Hall places certain Isonema, Pleurotomaria, Loxo- 
nema had perhaps an analogue in Europe in the Natica sub- 
piligera (Le flon) of the Devonian of Belgium. The same 
may be said of his new group Paleotrochus (one species), the 
casts of which resemble the Pleurotomaria Griffithii of MacCoy. 
Preropops.—Little has hitherto been known of the Paleo- 
zoic Pteropods of America; they had however acquired a 
great development in the Devonian era, for Mr. Hall has 
described thirty-two new forms, distributed in seven different 
genera. 
The Tentaculites which are represented in the Silurian 
Clinton Group of New York, and in the more ancient Trenton 
group in a neighboring State, have considerable diffgrences 
from the forms which are found in the Upper Silurian and 
i 
ences as generic ; and he limits the genus Tentaculites to forms 
which are conical, straight, elongated and covered with rings ; 
this genus thus defined first appeared in the Upper Silurian, 
and is represented by six speciesin the Devonian. The species 
of Tentaculites cited from the Lower Silurian appertain to the 
genus Cornulites, which attained its greatest development 
at this ancient period, and became extinct at the epoch 0 
the Niagara. The Tentaculites of the American Devonian have 
relations with the European forms of the same epoch ; thus 
we may compare 7. allenuatus (Hall) of America with the 7 
tenuis (Sow.) of England; 7. scalariformis (Hall) with T. sca- 
laris (Schit.). 
The genus Styliola is represented in America by two species, 
one of which presents four varieties; this species, Styliola Sis: 
surella, is very analogous to S. clavulus (Barr.); it has a wide 
geographical extent in the United States, where itis recognized 
enus Coleoprion of Sandberger is represented by 2 
The g 
doubtful form from the Hamilton group. Professor Hall has 
designated the genus Coleolus for six forms, of which the type 
C. tenuicinctum had been hitherto connected with the Cole 
oprion; these are tubular, conical forms, elongated, usually 
