1*76 



beak of upper valve small, distinct, marginal or submarginal. Surface 

 marked by fine, linear, radiating ribs, often dichotomous, sometimes 

 laterally undulated and crossed by concentric lines of growth, which 

 sometimes become squamose. Muscular scar large. Under valve 

 unknown." The second is the A. Vancouverensis, from " Departure Bay, 

 near Nanaimo," of which only the lower valve has been obtained, which 

 is thus described by Mr. Gabb : " Shell circular, thin ; upper valve 

 unknown ; lower valve flat, marked by strong lines of growth and by 

 very faint radiating lines ; aperture elongated, oblique, occupying 

 nearly a third of the diameter of the shell. Diameter one inch." Mr. 

 Gabb also remarks : " It is not impossible that this may prove to be the 

 under valve of A. lineata, nob., which belongs to the same group in the 

 same formation, and of which the lower valve is unknown." 



Pieces of the blackish or dark bluish-grey shales of Division B, 

 collected by Mr. Eichardson in 1871 on the banks of the Trent Eiver, 

 V. I., above the falls, are full of detached upper valves of a species of 

 Anemia, whicli the writer has very little hesitation in referring to A. 

 Vancouverensis. Ujjwards of sixty or seventy more or less perfect 

 specimens have been obtained, and many were unavoidably broken in 

 splitting up the pieces of shale in which they were imbedded, but not a 

 vestige could be discovered of the lower or perforated valve, although it 

 was carefully searched for. The upper valve is convex or compressed- 

 convex : its outline is very variable, the most common form being 

 transversely ovate ; the right side being produced and narrowly rounded 

 at the end, while the left side is short and broadly rounded at the margin. 

 Some specimens ai-e more elongated transversely than others, but the 

 length is always greater than the height. The beaks, which are small, 

 marginal, and not much elevated, are situated at varying distances 

 between the centre and the left margin, but are sometimes placed very 

 near the latter. The concentric striaa of the surface are well marked, 

 even on the cast, and where the test is preserved, which is not often the 

 case, it is covered externally with exceedingly minute and flexuous or 

 bent, radiating striae, which are too small to be seen with the naked eye, 

 and which can only be defined clearly by the use of a somewhat powerful 

 simple lens. Besides their own proper sculpture, these upper valves are 

 often impressed with the fine or coarse ribbing, as the case may be, of 

 other shells to which they were formerly attached, the most abundant 

 species with which they are associated being Ptychoceras Vancouverense 

 and Inoceramus mytilopsis. 



If the specimens last described are really the upper valves of A. . 



