MOLLUSCA. 437 



margins. On the thick, tortuous, even ends of these lamina, 

 the succeeding plate rests, and derives from them the pe- 

 culiar markings of its surface. These laminae are closely 

 set, irregularly interrupted, and occasionally anastomose. 

 M. CuviER states, erroneously *, that these laminae are 

 hollow pillars disposed in a quincunx order. 



The term bone has been improperly applied to this com- 

 plicated plate; " for," according to Mr Hatchett -f-, 

 '* this substance, in composition, is exactly similar to shell, 

 and consists of various membranes, hardened by carbonate 

 of lime, without the smallest mixture of phosphate." 



The most remai'kable species of this genus is the Sepia 

 officinalis, which is distinguished from the others by its 

 smooth skin. It inhabits the British Seas, and althoug-h 

 seldom taken, its bone is cast ashore on different parts of 

 the coast, from the south of England to the Zetland isles. 



% LoLiGO. Calamary. Sides of the sac only furnished 

 partially with fins. 



The suckers are disposed on the arms and feet in a 

 double row. The dorsal plate is flexible and corneous, im- 

 bedded in the substance of the sac, and is multiplied with 

 years. The following species occur in our seas 1. L. vul- 

 garis. 2. Sagittata. 3. Media. 4. Sepiola j. 



• Mem. sur la Seiche, p. 47. f Phil. Trans, vol. Ixxxix. p. 321. 



X 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 unfor- 

 tunate expedition under the direction of Captain Tuckby. These species be- 

 long to a group which have the suckers produced into hooked processes. In 

 two of these species, L. leptura and Smkfiii, the suckers on the arms, as well 

 as the feet, are produced into hooks, while, in one species, //. Banksii, the 



feet only are armed with hooks. 



The 



