13IYALYIA. 41 



5. Pecten duplicatus, /. Sowerby. Tab. VIII, fig. 10, a — c; and Tab. X, fig. 3. 



Pecten duplicatus. J. Sow. Min. Conch., t. 57 5, 1828. 

 — — Morris. Cat. Brit. Foss., p. 1/4, 1854. 



Spec. Char. JP. testa orbicirtari, dcpressd, radiald ; valvd dexlrd sublcevigald ; altera 

 costellatd ; costellis numerosis, imbricatis ; auricidis subceqiia/ibus. 



Shell orbicular, depressed, radiated ; one valve nearly smooth or with obsolete costae, 

 the other with thin rounded ribs, 14 to 1G, imbricated, increasing with age by the interpo- 

 sition of an additional rib ; auricles nearly equal. 



Diameter, \\ inch. 



Localities. Highgate, Primrose Hill {Wethcrcll), a, b,J\ Ilaverstock Hill, c, Muswell 

 Hill {Edwards). 



A strongly marked and ornamental species, and in the living condition probably a 

 handsome shell. The specimens in cabinets are by no means abundant, and rarely in good 

 condition. Mr. Sowerby, in ' Min. Conch./ represents one of his valves as quite smooth. 

 In all Mr. Edwards's specimens, the right valve has more or less depressed or obsolete costae, 

 and as many as thirty of these faint rays may be counted, and these are distinctly visible in 

 the interior. The left valve is ornamented with about sixteen thin, rounded, and imbricated 

 rays on the younger shell ; these are doubled, and again doubled, as the shell increases in 

 size, by the interposition of a rib ; they are all closely and regularly imbricated, but not the 

 interspaces. 



6. Pecten idoneus, S. Wood. Tab. VIII, fig. 9, a, b. 



Spec. Char. P. testa inaquivalvi ? suborbiculari, subdepressd, cequilaterali, costatd, et 

 concentrice sqaamulatd ; costis 13-15 elevatis, magnis,subquadrijpartitis ; auricidis, cequali- 

 bus radiantibus. 



Shell inequivalve? suborbicular, somewhat depressed, equilateral, costated, and 

 concentrically striated; ribs 13-15, elevated, large, and ridged; auricles equal and 

 radiated. 



Diameter, \\ inch. 



Localities. Hill Head, Stubbington {Fisher), Brook near Lyndhurst {Edwards). 



This is an ornamental shell, and appears quite distinct. It was first discovered by 

 the Rev. Osmond Fisher, who has obtained about a dozen specimens from the first locality, 

 and Mr. Edwards has very recently added three to his cabinet from the latter. 



In well-preserved specimens, the ribs are ornamented with one elevated and two lateral 

 ridges, dividing the surface of the rib into four portions ; the interspaces are about as broad 

 as the ribs themselves, in which a ray or two may occasionally be seen on the outer or 

 older portion of the shell ; the surface, when perfect, is ornamented with regularly concen- 



6 



