139 



and very gentlj^ downwards in front, descending abruptly and somewhat 

 obliquely, but not convexly, behind : posterior side very short and 

 contracted ; beaks small, curved backwards, not much elevated, placed 

 distinctly behind the middle; umbo apparently fissured, the fissure 

 narrow, slightly curved, and extending from the beaks about half-way 

 across the valves. Behind the umbonal fissure, and in the centre of the 

 space between it and the posterior margin, there appears to be a second, 

 but much shorter, impressed line. 



Surfixce marked by irregularly disposed, concentric stria of growth. 



Length, nine lines; height, eight lines and a quarter. 



Nanaimo River, V. I., two miles and a quarter up, in Division A ; J. 

 Eichardson, 18t2. A single perfect specimen, with both valves in 

 apposition. The left valve is partly buried in the rock, but it appears to 

 be the most convex of the two. The impressed line on theumbones may 

 indicate an acute, raised lamina on the inner surface of the valves, rather 

 than an umbonal fissure. 



Anatina sulcatina, Shumard. 



Plate 17, figures Sand 5a, 

 Anatina sulcatina, B. F. Shumard.— Proc. Boston Nat. Hist. Soc, 1861, Vol. 8, p. 204. 



Sucia Islands, in Division A ; J. Eichardson, 1875. Three fine speci- 

 mens. 



The following is Dr. Shumard's description of Anatina sulcatina: — 

 " Shell large, ovate, thin, inequivalve, very inequilateral : length not 

 quite equal to the ividth; anterior end broadly I'ounded ; posterior end 

 short, contracted, narrowly i-ounded ; pallial margin gently convex ; 

 beaks small, but little elevated, situated posterior to the middle; cardinal 

 margin straight, or very slightly convex before the beaks, and very 

 slightly arched behind ; a narrow, distinctly impressed, and very 

 gradually expanding sulcus, extending from beak to pallial margin, 

 which it cuts a little behind the middle ; surface with from twenty to 

 twenty-five rounded, concentric folds, becoming indistinct on the posterior 

 part of the shell. There are also many fine, concentric lines of growth 

 visible to the naked eye." 



"Length, Scinches; width, 1^ inches; thickness, 6|- lines." 

 " Eipley Group, Chatfield Point, Navarro County," Texas. 

 The measurements show that the length is rather more than twice 

 the width or height, and the words italicized in the above diagnosis are, 

 therefore, obviously incorrect. The transverse groove or sulcus, which 



