44 EOCENE MOLLUSCA. 



M. Deshayes, in speaking of the Paris Basin shell, P. plebeius, says it is variable, with 

 20 to 28 ribs, and he makes two varieties. 1 M. Nyst says of P. reconditas, from Belgium, 

 that he has seen but one valve, and this, judging from his figure, does not differ from our 

 shell. The specimens from Bracklesham, (as I have elsewhere said), figured by Mr. Sowerby, 

 and assigned with doubt to plebeius, most probably belong to SO-radiatus. 



There appears to be less variation of form in those bivalve shells whose outline is 

 circular or lenticular than there is in those whose normal condition is more elongated. 

 Pectens are, in general, I think, uniform in outline ; and when a specimen like the one 

 figured by Brander presents so great a difference, there is more reason to consider it as 

 belonging to a distinct species, than as a variety of one that is orbicular ; and it was only 

 after long and careful examination that I could, on that supposition, bring myself to believe 

 it to be only a variety. Brander's figure may, however, be the representation of a distinct 

 species ; if so, I have not seen it. 



9. Pecten squamula, Lamarck. Tab. IX, fig. 6. 



Pecten squamula. Lam. Ann. du Mus., t. viii, p. 354, No. 3, 1806. 



— — Id. Hist, des An. s. Vert., t. vi, p. 183, No. 27. 



— — Desh. Coq. Foss. des Env. de Par., t. i, p. 304, pi. 45, figs. 16—18. 



— — Id. An. sans Vert, du Bassin de Par., t. ii, p. 74, 1860. 



— — Id., 2d edit. Lamk., t. vii, p. 164, No. 34, 1836. 



— — ITOrbigny. Prod, de Palaeont., t. ii, p. 326, No. 528, 1850. 



— — J. Sow. in Dixon's Geol. of Sussex, pp. 94, 172, pi. 3, fig. 29, 1850. 



— — Morris. Cat. Brit. Foss., p. 179, 1854. 



— squamulosus. Desk. Ency. Meth. Vers., t. iii, p. 717, No. 7, 1832. 



Spec. Char. P. testa minima, rotundatd, depressd, csquilaterali, cequivalvi ; exttis 

 lavissimd, intus octo ad decern costatd ; auriculis magnis, subcequalibus. 



Shell minute, rounded, depressed, equilateral, equivalve ; very smooth externally, inside 

 with eight to ten costse ; ears large, slightly unequal. 



Diameter, \t\\ of an inch. 



Localities. — Bracklesham, Bramshaw {Edwards). 

 Prance, Chaumont et Laon {Desk.) 



This is exceedingly rare ; I have seen it only in Mr. Edwards's cabinet. It is a 

 miniature representation of P. pleuronectes, and, like that species, is externally smooth, and 



1 The shell from the Paris Basin appears to differ from our species. In some specimens of plebeius, in 

 Mr. Edwards's cabinet, sent to him by M. Deshayes, the rays are smooth at the top, rounded and imbri- 

 cated at the sides, and I cannot see the fine curving and diverging strise between the ribs which are so 

 distinct in P. reconditus. 



