. \N( III \ 

 WMtrlU 



In drawing up the above description 1 ha\e mad. t \peof the 



specie- which wa- d from tin- mu-eum of t!n> ( 'iiicinn.it i 



Hi-tory. This specimen is ;i mold of the exterior ami ha- I ..... n compreed in -uch 



a manner that tin- outline i- now niniat ur.illy quadrangular. tin- iiinl.oiial ridge too 



prominent ami tin- Leak- too narrow. I have eomp :. -fully with the 



northwestern -pecimen-. \\ Inch ar. -ft In- interior, ami wliilc I admit freely the 



the possibility of error, my coiiclu-ion for the |. resent is that they are specifically 



identical. 



Compared with other "f H'liiti-lln it will he finind that the shell 18 more 



erect and -horter. and the cardinal area wider than in any other known. \n osso- 



d form. CyrtotUmfa ///'//>. var lnculrnl-1 S.irde-on. ha* much smaller Keak-. while 

 they are al>o nearly in contact, the li^amental area being very much narrower. 



.UKl nMi. r 



iiii-ii> wi-ri- M|,I.H[|.M| from ai. n at Savannah, 



IlllnnN. irnl Spring 



' -OENSIS Mttk illl'l \\''if/ln-n. 



X and 9. 



:>>r<i itrrlinyrnii* MKKK '.il.id . p. 280; tlflo 



il. p. 339. 

 'terlingeiuii 'f M 133. 



Sliell rhombic-cordate, being cordate in outline, as seen in 

 an anterior and |>o~tein.r view, and ol>li|iiely rhoml>oidal, as seen from either - 



rior m.tix'in olili.|iiely truncated, \\ith a long slope, which i- -lightly convex 

 al>ove and faintly >inuou- near the middle; posterior liasal extremity jirod 

 oldinuely liackward- and downward-, with a more narrowly rounded or -ulian^iilar 

 outline; l>a^al in.irL'in a-cendin^r forward, with a moderately convex curve, and 

 rounding up more or l< iually into the OT aim" 



liinge line si irdiual area moderately developed. Iteaks promiu.Mif. 



placed nearly o\er the anterior marL'in. .-trongly incurved and compre-^pd an: 



riorly. 1'mlnnial ridge> very prominent, -ulian.- 'idin^ from the 



1 icaks oliliquely to ' r l.a-al extremity at an angle of al>oi. low the 



hori/.ou ot tin- hinge, thn- dividing each valve int .lieipial an-as of which the 



l-ehind i- flattened or -lighth - l)etween the ridge and the moderately 



prominent ; lor-al i-L'e. and that in front and In i Hinge and 



interir unknown.) 



"(i en^th. ine.i.-uring olilii|iiely from the ! 'he pn-teiior basal 



extremity. 'J. I'M iiH-lsc-; di:c ,t right ang .e >ame. 1 .",() n, 



of the two valves when l.'i" inches." 



