MARYLAND GEOLOGICAL SURVEY 703 



Outside Distribution. Magothy Formation. Cliffwood clay, New 

 Jersey. Matawan Formation. Merchantville clay marl, Woodbury clay, 

 Wenonah sand, New Jersey. Monmouth Formation. Bed Bank sand, 

 New Jersey. 



Superfamily SOLENACEA 

 Family SOLENIDAE 



Genus LEPTOSOLEN Conrad 

 [Am. Jour. Conch., vol. iii, 1867, p. 15] 



Type. Siliquaria biplicata Conrad. 



" Elongated, thin in substance, straight with the dorsal and ventral 

 margins parallel ; plicated anteriorly ; open at both ends ; beaks not nearly 

 terminal ; hinge of the right valve with one direct tooth, convex anteriorly, 

 truncated behind; an internal rounded direct rib commences under the 

 cardinal margin, gradually becomes less prominent and disappears towards 

 the ventral margin." Conrad, 1867. 



The ligament is external mounted on elongated nymphs. The pallial 

 sinus is very shallow. Dall l considers that the shell characters are inter- 

 mediate between those of Solen and Siliqua. 



The genus is restricted in its known distribution to the Middle and 

 Upper Cretaceous. 



A. Clavicular rib vertical Leptosolen biplicata 



B. Clavicular rib oblique, directed backward Leptosolen elongata 



LEPTOSOLEX BIPLICATA Conrad 

 Plate XL1I, Figs. 7, 8 



Siliquaria biplicata Conrad, 1858, Jour. Acad. Nat. Sci., Phila., 2d ser., vol. 



iii, p. 324, pi. xxiv, fig. 17. 



Siliquaria biplicata Gabb, 1861, Syn. Moll. Cret. Form., p. 226 (170). 

 Siliquaria biplicata Meek, 1864, Check List Inv. Fossils, N. A., Cret. and 



Jur., p. 15. 



Leptosolen Mplicata Conrad, 1867, Am. Jour. Conch., vol. iii, pp. 15, 138. 

 Leptosolen biplicatus Conrad, 1868, Cook's Geol. of New Jersey, p. 727. 



Etymology: XCTTTOS, thin; solen. 



1 Dall, 1900, Trans. Wagner Free Inst. Sci., Phila., vol. iii, pt. v, p. 950. 



