43 
Baculites. — Shell straight, cylindrical, sometimes rather compressed, slightly conical; 
the partitions articulated by sinuous sutures: septa transverse, a little distant; the 
disk imperforated, lobed, and indented at the circumference. 
Plate XXII. Fig. 14. B. Faujasii. Fossil. [Mr. G. B. Sowerby’s Cabinet.] 
Division II. — MONOTHALAMOUS CEPHALOPODA. 
Shell unilocular, wholly external, and enveloping the animal. 
Argonauta. — Shell univalve, unilocular, involute, very thin; spire bicarinated, tubercu- 
lar, turning into the aperture. 
Plate XX. Fig. 17- A. nitida. 
Division III NAKED CEPHALOPODA. _4 Genera. 
No shell either internal or external. A solid, free, cretaceous, or horny substance, is found in the 
inside of most of these animals. 
Octopus. — No internal solid substance. 
Loligopsis. — No internal solid substance. 
Loligo. — An elongated, thin, transparent, and horny lamina, inclosed in the interior of 
the body, near the back. 
Plate XX. Fig. 20. Lamina of L. vulgaris. 
Sepia. — A free, cretaceous, spongy, and opake bone, inclosed in the interior of the bo- 
dy, towards the back. 
Plate XX. Fig. 18. S. officinalis- 
ORDER V. 
HETEROPODA. 3 Genera. 
Carinaria. — Shell univalve, conical, flattened at the sides, unilocular, very thin, hyaline; 
the summit spirally turned, and the back sometimes furnished with an indented 
keel : aperture oblong, entire. 
Plate XX. Fig. 19. C. fragilis. [Icon. — Enc. Method. PI. 464, fig. 3.] 
Pterotrachea. — This genus has no shell. 
Piiylliroe. — This genus has no shell. 
G 2 
