BIVALVIA. 176 



2. AsTARTE PARVULA, S. Wood. Tab. XVII, fig. 1 1 a — b. 



AsTAKTE PARVULA. S. Wood. Catalogue, 1840. 



Spec. Char. Testa minima, obliqud, ovato-triangulari, inaquilaterali, compressiusculd, 

 subl(Bvi ; postice latiore : antice longiore, et productiore ; marc/ine integerrimo. 



Shell minute, oblique, of a triangularly ovate form, inequilateral, somewhat com- 

 pressed, nearly smooth ; posterior side very short and broad, anterior produced and 

 elongated ; margin smooth. 



Length, ^th of an inch ; height, yV^h ditto. 



Locality. Cor. Crag, Sutton. 



This is also an abundant shell at Sutton, but rarely obtained with the valves 

 united. It is a true Astarte, and may be distinguished from the preceding, which 

 is the species it most resembles, and for the young of which, without care, it might be 

 mistaken; its differences are principally in outline, this being much more inequilateral, 

 and in place of having the form of an imperfect equilateral triangle, like that of 

 A. triangidaris, the lines of the margins form with the umbo nearly a right angle ; 

 the posterior side is particularly short, with a very gentle curve to the ventral margin, 

 while the anterior is very much produced, sloping in a straight line to within a short 

 distance of the extremity, considerably reducing the breadth, or rather height, of that 

 side ; the hinge is furnished with one large triangular tooth in the right valve, as in 

 all the species of the genus, with two in the left, and the prominent marginal or 

 lateral tooth of the right valve, which fits into a corresponding depression in the left, 

 is on the posterior side, while on the anterior side of the umbo, the elevated ridge is in 

 the left valve, and at a considerable distance ; the exterior is generally smooth, but in 

 perfect specimens, obsolete, concentric ridges, though not very regular, may be 

 detected. . 



The shell in its recent state was probably of a reddish-brown colour, like the 

 preceding species, traces of which remain in some specimens, and in others it is also 

 formed into concentric bands. The margin in all my specimens is free from the least 

 appearance of crenulations, as well in those which are the largest, and presumed to be 

 full grown, as in the smaller and consequently younger. 



3. Astarte borealis, Chemnitz. Tab. XVI, fig. 3 a — d. 



Venus borealis. Chem. Conch. Cab. vii, t. xxxix, fig. 412, 1784. 



— COMPRESSA. Mont. Test. Brit. Snppl., p. 43, t. xxvi, fig. 1, (large fig.) 1808. 



— SULCATA. Mat. and Rack. Linn. Trans., vol. viii, p. 81, t. ii, fig. 2, 180". 

 Astarte plana. J. Sow. Min. Conch., t. 179, fig. 2, 1817, (not Nyst.) 



— — Id. Geol. Norf., p. 43, t. ii, fig. 14, 1833. 



— borealis. S. Wood, Catalogue, 1840. 



— — Phil. Neuer. Conch., vol. ii, p. 58, Astarte, pi. i, fig. 11. 



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