MOLLUSCA;_ 135 
The term done has been improperly applied to this com- 
plicated plate ; “for,” according to Mr. Hatchett, (Phil. 
Trans. vol. 1xxxix. p. 321.) “ this substance, in composition, 
is exactly similar to shell, and consists of various mem- 
branes, hardened by carbonate of lime, without the small- 
est mixture of phosphate.” 
“The most remarkable species of this genus is the Sepia 
officinalis, which is distinguished from the others by its 
smooth skin. It inhabits the British seas, and although 
seldom taken, its bone is cast ashore on different parts of 
the coast, from the south of England to the Zetland isles. 
Genus Lorico. Calamary. Sides of the sac only fur- 
nished partially with fins. 
The suckers are disposed on the arms and feet ina 
double row. The dorsal plate is flexible and corneous, im- 
bedded in the substance of the sac, and is multiplied with 
years. Dr. Leach has described three new species of the 
genus Loligo, which were collected by Mr. Cranch during 
the voyage to the Congo, in that unfortunate expedition 
under the direction of Captain Tuckey. These species be- 
long to a group which have the suckers produced into hook- 
ed processes. In two of these species, Z. leptura and 
Smithii, the suckers on the arms, as well as the feet, are 
produced into hooks, while, in one species, Z. Banksii, the 
feet only are armed with hooks.’ 
The same distinguished naturalist has instituted a new 
genus nearly allied to Loligo, from two species collected 
during the same voyage. The following characters are as- 
signed to it. 
“ Genus CrancntA.—Body oval, sac-shaped; fins ap- 
proximating, their extremities free; neck with a frenum 
