Bivalve Shells of Nova Scotia. 127 



Supplement to Acadian Geology, 1860, p. 43 (as Naiadites) ; Salter, 

 Journal of Geological Society, Vol. XIX, 1863, p. 79 ; Acadian 

 Geology, second edition, 1868, p. 204; Wheeltori Hind, Journal 

 of Geological Society, Vol. L, 1894. 



This species is characterized by an obliquely ovate form 

 in typical specimens the length being about double the 

 breadth. The umbones are somewhat elevated and near the 

 narrower anterior end. The straight hinge-line is somewhat 

 oblique and a little more than one-third of the length of the 

 shell. The front margin is slightly sinuated, the posterior 

 margin regularly rounded. The surface is smooth and 

 shining, with concentric lines of growth. 



This is by much the most abundant species, and is very 

 variable in form and size. When aged, it is more elongated 

 than when immature, and the hinge-line is relatively 

 shorter and less elevated. It often has shells of spirorbis 

 attached, and occurs in patches in beds holding vegetable 

 fragments, in a manner to suggest that it may have been 

 attached to these. 



The collection in the Peter Redpath Museum contains 

 specimens from various members of the Carboniferous 

 system, and from the South Joggins, Pictou, Sydney, Glace 

 Bay, Mabou, Riversdale, Swan Creek and Parrsboro. The 

 shells from the three latter places are from beds low down 

 in the system, and are of small size. In general form this 

 shell resembles A. Williamsoni, W. Hind, of the English coal 

 measures, but is less elongate. 



2. Anthracomya laevis, Dawson. 



Fig. 9.— Anthracomya laevis, Middle Coal-formation, S. Joggins, 

 natural size, and enlarged. 



