BIVALVE SHELLS. 235 



number or position; but there are generally two or three, the shell 

 appearing as if it consisted of three or four thin valves, of different 

 sizes, adhering to one another. This fossil and No. 11 have 

 generally a reddish or brownish hue. They are both flat and thin 

 shells. In honour of Malton, where so many interesting fossils are 

 obtained, we may name this shell p. Maltonensis* 



No 6, from the ironstone bands of the aluminous strata, is 

 perhaps another nondescript. It is the cast of a shell resemr 

 bling p. Danicus ( or ostrea triradiata ), having very unequal ears, 

 the valves marked with very minute longitudinal striae, and with 

 four or five ribs or elevated plaits ; the ends of which project at 

 the margin, the intervening marginal spaces being either straight or 

 slightly bent inwards ; giving the shell the appearance of the webbed 

 foot of an aquatic fowl. Some of our specimens are three inches in 

 diameter, which is double the size assigned to p. Danicus. Should 

 our shell prove a new species, we would name it p. cygnipes. 



No. 4, from the same strata, is perhaps the flat valve of a smaller 

 shell of this species, having markings somewhat similar ; but it has no 

 angular points in the margin; the plaits, though corresponding in. 

 number, are not elevated but sunk ; and instead of proceeding to 

 the margin, disappear at about two thirds of the length from the 

 beak. This valve is rather concave in the middle ; and is marked, 

 near the margin, with two or three transverse rings, or lines of 

 growth. If this shell belong to the same species as No. 6, it cannot 

 be the p. Danicus ; but it is not unlikely to be another species. 



Nos. 2 and 7 are of that class of pectens which have a crooked 

 appearance, leaning or bending to one side. No. 2 is very abundant 

 in the ironstone and sandstone beds of the aluminous strata. It is a 

 smooth shell, marked with about ten slender ribs, handsomely bent ; 



* Specimens of most of the Malton fossils may be procured from Mr. John Larkum of that 

 placBj an indefatigable collector. 



