XATURAL SCIKSCR5 OF PHILADELPHIA. So 



COXTLABIA ELEGAirrCLA. M^-ek. 



Shell presenting the usual quadrangular pvraniidal form, with 

 the di\-ergence of the sides from the rather jx>intevl ajx^x, fonuinij 

 an angle of about IS degrees: each of the four lateral angles 

 slightly rounded and distinctly furroweil : sides equal, nearly 

 flat, and without any well define*.! longitudinal mesial furrow. 

 Surface ornamented by numerous, very small, closely arrang^^l, 

 transverse lines that arch gently forwarxl or towani the aivrtuiv, 

 and sometimes become slightly interrupted and alternating along 

 the middle of each side; while in other instances they are merely 

 a little deflected and continuous across this slight impression or 

 imaginary line. These lines attain their largest size, and are 

 separated by spaces of their own breadth, at about O.TO inch from 

 the apex, and beyond this l»ecome gradually smaller and mor« 

 crowded toward the aperture. AVheiv largest and widest apart, 

 they number about seven in one-tenth of an inch. They aiv all 

 erenulated, thei-e being fourteen of the crenulations in a length of 

 one-tenth of an inch. Furrows K^tween the transverse lines 

 marked by very fine strife, much smaller and more cn^wded than 

 the crenulations on the strijv, and running in the diivction of the 

 longitudinal axis of the shell. 



Length of specimen, apparently nearly entire, 1.70 inches; 

 breadth, about 0.50 inches. 



This species is related to C. bi/bUs of White ^^Proc. Bost. Soc, 

 y. H.. Feb. 1S62, p. 22), and C. »m<//j(W/a/(i, M. ^t W. ^Proc. 

 Acad. Sci.. Phila., Pec. lSt>o, p. 252\ from the Waverlcy group 

 of Iowa and Ohio. It diflers, however, in having its transverse 

 lines smaller and more crowded, there being about TO of them to 

 the inch, at the point where they are largest and widest apart, 

 and 100 in the same space near the larger end of the shell; while 

 in both of the Waverlcy species mentioned, only forty-live to firty 

 occur in an inch. The crenulations of the transverse stria^ an' 

 also smaller and more crowded in the species under considcraiion, 

 there being usually fourteen of them in one-tenth of an inch, which 

 would oive 140 to the inch; while, according to Prof. WinchcU's 

 measurements, they are so much larger and more distant in (\ h(/- 

 blis, that GO to 75 of them would occupy the same space. Tiio 

 obtusely rounded and smooth apex mentioned in Dr. White's de- 

 scription, if natural, would be another very important distinction; 

 1S71.] 



