S 



WORM S. 



55. Pbhas. 



Shell bivalve : with accefTory valves at the 



hinge. 



B. Bivalves : Jhell ivith 2 valves, Conchs. 



56. Mya. • Hinge with generally a broad thick tooth, 



not let into the oppofite valve. 



57. Solen. Shell open at each end: hinge with a finale 



or double fubulate reflected tooth, not let 

 into the oppofite valve. 



Hinge with the lateral teeth of one valve not 

 let into the oiher. 



Hinge with remote penetrating lateral teeth. 



Hinge with a complicated triangular middle 

 tooth, and an adjoining hollow. 



Hinge with a generally remote lateral tooth, 

 not let into the oppofite valve. 



Hinge with generally 3 approximate divari- 

 cate teeth. 



Hinge with 2 teeth feperated by a fmali 

 hollow. 



Hinge in one fhell, with 2 oblique obtufe 

 teeth. 



Hinge with numerous penetrating teeth. 



Hinge without teeth, but an ovate hollow. 



Hinge without teeth, but generally a linear 

 depreflion on the rim, the beak of one 

 valve curved over the hinge. 



Hinge without teeth, with a fubulate de- 

 preflion, and generally fixed by a filky 

 beard. 



Hinge without teeth: valves united at one. 

 end and open at the other. 



58. Tel Una, 



59. Cardium, 

 ho. Madlra. 



61. Donax. 



62. Venus. 



63. Spondylus. 



64. Chama. 



65. Area. 



66. OJirea. 



67. Anomla. 



68. Myt'dus. 



69. Pinna. 



70 



71. 



Argonauta. 

 Nautilus, 



7 2 - 

 73- 



Conus. 



Cypraa. 



74* 



Bulla. 



75- 



Valuta. 



C. Univalves, zUltb a regular fplre. 



Shell with one cell, fpiral involute. 

 Shell with many cells, with a hole of com- 

 munication. 

 Aperture efFufe longitudinal, without teeth. 

 Aperture efFufe linear longitudinal, toothed 



each fide. 

 Aperture a little contracted and placed ob- 

 liquely. 

 Aperture effufe ; the pillar plaited. 



76. Buccinum* 



