91 
SANGUINOLARIA undulata. 
TAB. DXLVIII. —figs. I & 2. 
Spec. Char. Three times as wide as Jong, trans- 
versely undulated,, convex ; anteriorly round- 
ed, posteriorly subtruncate, gaping a little ; 
fulcra prominent. 
A shell in general form much resembling some spe- 
cies of the Linnaean genus Mya ; but its great width and 
the external situation of the ligament, pointed out by 
the fulcra, indicate an approach to the Linnaean genus 
Solen, of which Sanguinolaria is a portion. 
The undulations of its surface are peculiar; they 
gradually disappear upon the posterior portion : the 
shell is thin and smooth, internally a little pearly. 
One of the most remarkable fossils collected by R. I. 
Murchison, Esq. in the district of Brora. It occurs in 
the peculiar bed that forms the roof of the coal, consist- 
ing of argillaceous limestone of a soft texture and gray 
colour in the pits where coal is now worked (fig. 1.), 
but hard and of a red-brown in the rocks opposite the 
Old Salt Pans (fig. 2.). The fossils that accompany this 
will be fully detailed in Mr. Murchison’s forthcoming 
Paper. 
