491 
TROCHOLITES SCOTICUS. 
NautiLus (Trocu.) scoticus, Blake (Briz. Ceph., Pl. xxix, Fig. 6, 
Pio scKvil, TA). 
Blake’s figures show sutures, but he states that none are discern- 
ible. The aperture and form of whorl and striz indicate that this 
is a species of Trocholites. 
Hercoceratide. 
? 
In ‘¢ Carboniferous Cephalopods,’’ second paper, Fourth Annual 
Report Geol. Survey of Texas, | separated the Tainoceratide, includ- 
ing the Temnocheilus, Metacoceras and Tainoceras from the Her- 
coceratidz, but further study leads me to think that this is not 
advisable considering the approximation in form and characters of 
the two sets of genera and have reunited them here under the old 
name. 
In genera of fossil Cephalopods I regarded J?¢yssoceras (Cyrt.) 
alienum, sp. Barrande, as the arcuate radical type of this family. 
It has a single row of large, lateral tubercles, sutures nearly straight, 
whorl in section depressed, elliptical and siphuncle ventral, and it 
has no dorsal furrow. The genera properly included under this 
family name are as follows: 
Ptyssoceras, Trochoceras, Hercoceras, Anomaloceras, Lower 
Silurian ; Centroceras, Devonian; Temnocheilus, Devonian to 
Dyas (Permian); Metacoceras, Tainoceras, Carboniferous and 
Dyas; Foordiceras,* Dyas. 
I have also provisionally placed Coelogasteroceras in this family 
on account of the general resemblances of the form of the nepionic 
stage, the smooth shell and the hollow ventral zone in the abdomen. 
Ptenoceras,} n. g. 
Under this name I propose to place all those forms formerly in- 
cluded under the name of Hercoceras in my Genera of Fossil 
Cephalopods, whether turbinate or coiling in the same plane, which 
have no impressed zone at any stage. The whorls are open, or 
barely in contact, and are rounded in the early stages and subquad- 
ragonal later in life. The apertures are similar to those of Herco- 
* All these genera are mentioned or redescribed below as far as needed for the pur- 
poses of this paper except Foordiceras and Tainoceras, which haye been described in 
“ Carboniferous Cephalopods,”’ quoted above. 
t [zyyés, winged. 
