3HA33.VTELLI J^o i .->^.„,^uxiii , ^tLMoPIoSUS n. sp* 



Descri-^ti ' .. .- Shell of mediimi size, hecvj-^, de^idedlv con- 

 vex, t ■." rnclj? elong-ate, rno derate Ij? ineoiiilateral ; posterior 

 dorsal mare-in eTioavated, abruptly ro\mded anteriorly, obliquely 

 truTiCTte-l T^osteri orly, base slightl y emarginptf-^ri before the car- 

 ina; imbones high, decidedly incurved, the apes flattened; es- 

 cutcheon slightly vrfLder and longer than the limule, both moder- 

 ately impresre''. ; poBtr--"!-;!- carina v/eal-r; running from the umbo to the 

 upoer edge of the posterior trimcation a second, lov;er and broad- 

 er carina present; sculpture of niiie concentric ujadulations in the 

 umbonal region, "f^bp v^^ntrel few slightly crowded; on th'= anterior 

 slope finer concentric undulations continuous almost half of the 

 distance from the umbo to the ventral margin, the remainder of 

 the shell smooth except for incremental lines; hinge "-^'^'^^ '^as::ive, 

 the right posterior cardinal relatively conspicuous; inner margin 

 of the VHlve smooth. 



■Qinensions .- length 61 mm.; al-f-., '5 mm.; seraidiam., 18 mm. 



iAemarlrs_.- i'his species^ which is based on a single adult 

 right valve and a very young right valve_, is very closely relcted 

 to the Oak Grove 2* densus Pall (1), bi,it differs by bring propor- 



(1). Trans. V/agner ?ree Inst. Soi., Philadelt)hia, vol. ?, vit, 5, 

 pl. 59, figs. 9-lf^, 1900; idem, nt. 6, p. 1472, 1905." 



