386 



"The species may now be provisionally named and characterized as 

 follows : — 



- Unio Nanaimoensis (Sp, nov.) " 



" Shell compressed-convex, ovately subelliptical, much longer than high, 

 higher than broad, and very inequilateral. Anterior end short, rounded ; 



posterior end much 

 longer than the an- 

 terior, its extremity 

 obliquely subtrun- 

 cate above, produ- 

 ced and somewhat 

 narrowly rounded 

 below ; beaks pla- 

 ced in advance of 

 the mid length ; pos- 

 terior umbonal slo- 

 pes not at all angu- 

 lated. 



" Surface marked 

 only with numerous 

 concentric lines of 

 growth. Hinge den- 

 tition, muscular im- 

 pressions, and pal- 



FiG. 21. — Unio Ifanaimoensis.— Side view of the only specimen Hal line unknown. 



known, in outline. 

 Tig. 27a.— Dorsal view of the same, also in outline, to shew the " Approximate 

 proportionate convexity of the closed valves. dimensions of the 



Both the figures are of the natural size. «>^ ecimen figured : — 



Maximum length, 

 sixty-eight millimetres ; greatest height, thirty-seven millimetres ; maxi- 

 mum breadth or thickness, twenty-four millimetres. 



" The slight distortion and somewhat slickensided movement to which 

 the specimen has been subjected has so displaced the normal position of 

 the valves that the marginal outline is not as distinctly defined as might 

 be desired, and the beaks are no longer quite opposite. 



"As compared with U. Nanaimoensis, U. ^tt66arc?t is a much more con- 

 vex shell, with distinctly angular or subangular posterior umbonal slopes, 

 and it is much more attenuate posteriorly " (op. cit. supra.). 



