( 30 ) 



3. LinCula, Lam. M. 



Sub- equivalved, flat- Hinge without teeth, 



tened, oblong-oval, trun- (1) 

 cated at the summit, a 

 little pointed at the base, 

 raised on a fleshy ten- 

 dinous pedicle affixed to 

 marine bodies. Fig. 99. 



4. Spirifer. Sowerby. 

 Foss. 



Equilateral, inequival- 

 ved, one valve with a large 

 angular sinus along the in- 

 side of the beak. Fis*. 101. 



5. MkGAS.Sowerbj-.Foss. 



Equilateral, inequival- 

 ved, one valve with an 

 angular sinus along an in- 

 curved beak; back of the 

 other valve straight, with 

 two projections near the 

 middle. Fig. 100. 



6. Pentamerus. Sowerby. 



Foss. 



Equilateral, inequival- 

 ved ; one valve divided 

 by a longitudinal internal 

 septum into two parts, the 

 other by two septa into 

 three parts or valves ; 

 beaks incurved, imper- 

 forate. (4) Fig. 103, 104. 



Hinge transverse, long 

 and straight, two spirally 

 coiled linear appendages 

 to the hinge, nearly fil- 

 ling the shell. (2) 



Line of hinge straight, 

 a partial longitudinal 

 septum with appenda- 

 ges attached to the hinge 

 within. (3) 



(1) There is but one species known; from the Indian Seas. Foss. in the London 

 Clay, Crag Marl, Coal Shale. 



(2) The Terebratula spirifera of Lamarck, which is only known in a fossil state, 

 and is found in the Derbyshire Peak Limestone. 



(3) In Chalk. 



(4) I have hesitated in putting this shell amongst the Bivalves, suspecting that 

 the septa mentioned by Mr. Sowerby, may prove to be a number of valves 

 soldered together; but until it is perfectly known, it may be premature to 

 alter his classification of it as a Bivalve. It is found in the Derbyshire Peak Rock. 

 I add Mr. Sowerby's figure and description of the Axinus (fig. 102), being 

 too imperfect to admit of its classification, as memoranda for the geologist. 

 " A free, equivalved, transverse, bivalve; anterior side very short; posterior 

 " side produced, truncated, with a lunette near the beaks : hinge with a long 

 tc oblique ligament placed in a furrow. It is much to be regretted that there 

 tc is very little probability of discovering the interior structure of the hinge, 

 " but I suspect it has no teeth. The shell appears to be thin, but I can trace 

 " neither the cicatrices of the muscles, nor of the edge of the mantle in the 

 " Jngulatits, which I consider the type of the genus," 



