286 
TABLE OP GENEEA- 
II. BIVALVES. 
Shell formed of two valves, connected together by a ligament 
on the dorsal edge. 
* Shell with diverging hinge-teeth ; inside not pearly, 
Cyclas. Shell oblong, nearly equilateral. — ^p. 252. 
PisiDiuM. Shell ovate, inequilateral. — ^p. 264. 
** Shell with irregular hinge-teeth ; inside pearly, 
Unio. Shell with distinct posterior lateral laminar teeth. — 
p. 278. 
Alasmodon. Shell without any lateral teeth. — p. 276. 
Hinge toothless, 
Anodon. Shell ovate, pearly ; umbones (dorsal) blunt.— p. 271. 
Dreissena. Shell triangular, not pearly ; umbones (anterior) 
acute. — p. 259. 
IL 
AN OUTLINE OF THE HISTORY OF THE VARIOUS ADBITIONS 
WHICH HAVE BEEN MADE FROM TIME TO TIME TO THIS FART 
OF OUR FAUNA. 
1st. Merret, who in 1667 published the first attempt at a 
British Fauna, in his Pinax,, has recorded six species 
1. Anodon cjgneus (^Mytilus^ or Horse Muscle). — 2. Lim- 
neus (Z. stagnalis f). List Ang, t. 2. f. 1. — 3. Limax maxi- 
mus. — 4. Helix Pomatia, which he says is found in Sussex. — 
5. Helix rufescens {Cochlea alba minor uhique in hortis), — 6. 
Helix nemoralis {Cochlea vulgaris testa variegata). List, Ang, 
t. 2. f. 3. 
2nd. Dr. Lister, in 1678, commenced a separate work on 
the British shells and, as was to be expected from his accuracy 
and the extent of his researches, he may be considered as the 
originator of this part of the science. He described and figured 
in this work, and in his larger work on conchology (where he 
marked the British species with an A), the following species, 
