373 



rounded, but faintly subangular at the midheight in marginal outline, the 

 foot opening of moderate size, and closed with a callous plate, or thin 

 calcareous deposit ; posterior side somewhat attenuate, longer than the 

 anterior and more narrowly rounded at its termination exteriorly; ventral 

 margin nearly straight at and behind the midlength ; superior border 

 sloping abruptly downward in front of the beaks, and much more gradu- 

 ally so behind them ; beaks placed in advance of the midlength but not 

 quite terminal : accessory valves, if any, unknown. 



Surface marked with an obliquely transverse, narrow umbono- ventral 

 groove that is bounded on each side by a row of minute punctures, and 

 by concentric striations or sulci, that are coarser behind this groove thaa 

 in front of it. 



Interior of the valves unkn >wn. 



Dimensions of the specimen figured : length, ten millimetres and a 

 quarter : maximum height, five mm. and three-quarters. 



Extension mine, near Nanaimo, V.I., W. Harvey, 1901 : the right 

 valve figured, which is now in the Museum of the Survey. 



This little shell is not nearly so attenuate behind nor so ventricose 

 anteriorly as the Vancouver Island specimens of Martesia clausa, Gabb, 

 that are described and figured in the second part of this volume.* It is 

 by no means certain that the former is a true Martesia. 



Cymbophora Ashburneri, Gabb. 



1. Large ribbed variety. 



Mactra Ashburneri, Gabb (pars). 1864. Geol. .Surv. Calif., Pklaeont., vol. i, p. 15.3. 

 Cymbophora Ashhiirneri, Gabb (pars). 1869. Idem, vol. ii, p. 181. 



Whiteaves. 1879. This volume, pt. 2, p. 141, pi. 17, fig. 8. 



Shell comparatively large ; whole surface concentrically ribbed, the 

 ribs separated by deep grooves, and both ribs and furrows minutely and 

 concentrically striated. 



Specimens of this form of C. Ashburneri were collected b}'' Mr. James 

 Richardson at Blunden Point, Vancouver Island, in 1871 ; at Hornby 

 and Protection islands in 1873; and at the Sucia islands in 1874. 

 Similar specimens have since been collected at the Sucia Islands by Dr. 

 C. F. Newcombe, in 1894; at Brennan Creek, V.I., and at Protection 

 Island by the Rev. G. W. Taylor, in 1901 ; also at Protection and Texada 

 islands by Mr. Harvey, in 1901. 



*0n page 137, and Plate 17, figs. 2, 2 a and 2 h. 

 5 — M. F. 



