AMERICAN PALEOZOIC CEPHALOPODS 
209 
The first species described by Hall under Endoceras is sub- 
centrale Hall from the Black River (Watertown) at Watertown, 
New York. The type specimen of this species is numbered 603 
in the American Museum of Natural History. The figure pre- 
sented by Halh® shows only the middle half of the specimen and 
is printed in an inverted position, with the apical end directed up- 
ward. Liberties were taken in the preparation of this figure. 
An endocone is present, as in the figure, but the septal necks ap- 
pear to extend posteriorly for a distance of two camerae, the 
lower half of each septal neck invaginating into the upper half 
of that next beneath. If emphasis be placed on the lack of nu- 
merous endocones, then Endoceras subcentrale is as typical an 
example of Endoceras as proteiforme Hall, the genotype accepted 
by Bassler.i^ If emphasis be placed on the elongation of the sep- 
tal necks, then it agrees in this respect with typical Vaginoceras. 
The present writer regards it as an Endoceras. 
The second and third species described by Hall under Endo- 
ceras, namely longissimum and multitabulatum, belong to Hy- 
att’s genus Vaginoceras. The fourth species, gemelliparum, ap- 
pears to be a typical Endoceras. The fifth species is the geno- 
type of a new genus, Cyclendoceras, established by Grabau and 
Shimer. The sixth species, proteiforme, is accepted by Bassler 
as the genotype of E^idoceras, since this is the species best known, 
and represented by the greatest number of specimens. 
In describing Endoceras proteiforme. Hall discriminated five 
varieties, namely tenuistriatum, temdtextum, lineolatum, strang- 
ulatum and elongatum. Of these, tenuistriatum, tenuitextum, 
and lineolatum are referred by various authors to Orthoceras. 
The variety strangulatum is another Orthoceroid. Only elonga- 
tum remains as a probable Endoceroid. 
Typical Endoceras proteiforme Hall is represented by the fig- 
ures on Plates 48, 49, 50, 53 and 57. The original of Figure 4 on 
Plate 48 is selected here as the type of the species. The speci- 
mens figured on Plate 49 are regarded as cotypes. Owing to the 
importance of this species in the diagnosis of the genus Endo- 
ceras, it is described more fully in the following lines. 
Hall J., Pal. New York, vol. 1, 1847, pi. 17, fig. 4. 
” Bassler, R. S., Bibliographic Index of American Ordovician and Silurian 
fossils; U. S. Nat. Museum Bull. 92, p. 480, 1915. 
