MOLLUSCA. 405 



1886. Breviaraca Saffordi Whitf., Pal. N. J., vol. i (Monog. 



U. S. G. S., vol. 9), p. 87, pi. 12, figs. 11-12. 

 1905. Area saffordi Johns., Proc. Acad. Nat. Sci. Phil. (1905), 



p. 9. 



Description. — "Shell rather small, ovately trapezoidal in out- 

 line, with strongly ventricose valves and largfe, tumid, subcentral 

 beaks, which, stand prominently above the hinge line, are in- 

 curved and approximate. Hinge line about two-thirds as long 

 as the entire length of the valves, with a moderately high, ver- 

 tically striated area, the striated portion being bounded by a 

 plain border over which the striations do not extend. Anterior 

 end sharply rounded and the basal line round and full. Posterior 

 extremity oblique, extended somewhat below and rounding into 

 the basal line. Posterior umbonal ridge rounded but quite dis- 

 tinct. Surface covered entirely with fine, slightly raised thread- 

 like striae, which are somewhat alternating in size on the postero- 

 cardinal slope. Hinge plate moderately wide and distinctly 

 arched on the inner margin, the line of teeth more distinctly 

 arcuate. Teeth numerous, narrow, and diverging- outward from 

 beneath the beak, and gradually increasing in length to near the 

 outer ones. Muscular impressions proportionally large and dis- 

 tinct, the posterior one having a slightly raised line on its anterior 

 margin, but only seen in the larger specimens." (Whitfield.) 



Remarks. — The specimens in the recent New Jersey collections 

 which have been referred tO' this species, are all internal casts 

 from the Woodbiiry clay; they vary considerably in form, some 

 of them being about as oblique as Whitfield's illustration of B. 

 saffordi, while others are almost exactly equilateral and have the 

 aspect of a small, strongly convex Axinea. It seems to be im- 

 possible, however, to separate the oblique specimens from the 

 equilateral ones, as all intermediate variations seem to exist. 

 The species differs from B. cuneata, with which -it is associated, 

 in its smaller size, often by its more equilateral form, and by the 

 less conspicuous concentric markings of the shell. 



Formation and locality. — Woodbury clay, Lorillard (102), 

 near Matawan (103), near Haddonfield (168). 



Geographic distribution. — New Jersey, Tennessee. 



