BIVALVIA. 45 



has its rays or costse upon the inner surface : the exterior seems to have been glossy, and 

 the left valve was probably ornamented with colour in zigzag, somewhat like P. similis ; the 

 shell is extremely thin, and the internal costae can be distinctly seen on the outside. The 

 auricles arc large, as is usually the case in minute species of this genus, and the one on 

 the pedal side is the larger of the two ; this in the right valve is rounded at the angles, and 

 ornamented with about half a dozen elevated and imbricated rays, and sinuated near its 

 junction with the shell. In the left valve, the auricle on the pedal side is also larger, but 

 it is neither rounded at its upper angles, nor sinuated beneath. It is most probably 

 identical with the Paris Basin shell, and is not very distantly related to another small 

 fossil species, P. squama, Scac. (P. pt/gmat/s, Miinst.), but this is said to be furnished with 

 as many as twenty rays on the inside of the valves. The figure with this name in ' Goldf. 

 Pet. Germ.,' pi. 99, fig. 6 a, b, appears a larger shell ; but it has the same number of internal 

 ribs, and corresponds in other respects. Nilsson, ' Petrificana Suecana,' p. 24, t. ix, fig. 18 

 a b, describes a species, P. inversus, which is intermediate in size between squamula, 

 Goldf., and pygmceus, Miinst. 



Pecten squamid a (Geinitz 'Charak. der Schicht unci Petr, des Sach. Bohm Krcid,' p. 83, 

 taf. xxi, fig. 8) is altogether a different species. 



10. Pecten 30-radiatus, /. Sowerby. Tab. IX, fig. 4, a — h, -and Tab. VIII, fig. S. 



Pecten 30-radiatus. J. Sow. in Dixon's Geol. of Suss., p. 172, t. 3, figs. 30, 31, 1850. 



— 40-radiatus. Id. - - '- p. 173, fig. 33. 



— plebeius. Id. - - - p. 172, figs. 28, 32. 



— multistriatus? Morris. Cat. Brit. Foss., p. 178, 1854. 



Spec. Char. P. testa variabilis, cequivaloi, orbiculari, radiatim cost aid, costis numerosis, 

 rotinidis vel anguJato-sulcaiis ; interstitiis inter dum squamidis, minimis, aspcratis ; quan- 

 doque radiatis ; auriculis inceqxalibus. 



Shell variable, equivalve, orbicular, with numerous ribs, rounded or subangulated ; 

 interspaces sometimes with small, rough scales or lines of growth, sometimes with an inter- 

 mediate ray ; auricles unequal. 



Diameter, l|ths inch. 



Localities. Bracklesham, Bramshaw {Edwards). 



The deposit at Bracklesham Bay has yielded an abundance of specimens belonging to 

 the genus Pecten, and these present, an unusual amount of variation, rendering a specific 

 determination a task of extreme difficulty. Mr. Edwards had previously examined his 

 specimens ; the accompanying notes were in his cabinet, and I have his permission to 

 transcribe them : 



