No. 4.] 



BILLINOS — FOSSILS OF NE^.TOUI^DLAND. 



469 



The shell which, is supposed to be the ventral valve of thi« 

 species, is gently convex, with usually a somewhat flat space 

 extending from the front margin upwards towards the beak. 

 The apical angle appears to bo from 00 to 100 degrees. Shell 

 very thick, of a lamellar structure, dark brown or nearly black, 

 and, sometimes, whore exfoliated, of an ashy grey colour. Sur- 

 face with a number of obscure undulations of growth and with 

 fine longitudinal strijc, about ten in the width of one line. 



* Cruziana similis, spec. nov. 



I 



Fir. f). Cruziami Kunilix ; 7, tlie median pjronvc : r, r, the ridges at 

 iho sides. 



The specimens arc from twelve to fifteen lines wide, divided 

 along the middle by an angular groove, and bordered on each 

 side by a narrow ridge, about one line wide. The spa(!0 on each 

 side between the median groove and the marginal ridges, are 

 moderately convex and cro.sscd obli([uely by numerous irregular 

 raised lines, with furrows between them. These lines usually 

 have the form of a gentle sigmoid curve, sometimes extending 

 (juite across, but are often «« — ^ -d together in a somewhat con- 

 fused manncT, still preserving ihe gentiral oblique direction. 

 Upon an average there are about ten lines in the 1 mgth of half 

 an inch. The marginal ridges arc sometimes longitudinally 

 striated. 



This species has been heretofore referred by me to C. semi- 

 pUcata, Salter, but although closely allied, none of our specimens 

 agree exactly with the figures of the British species. 



Besides the above six species, many of the beds of sandstone 

 of Great Boll Island, arc covered with several species of Pal(eo- 



V 



C;- .>CL fU / 



