377 



elliptical, about one fourth longer than high and almost equilateral. 

 Anterior and posterior sides about equal in length, their extremities, 

 narrowly rounded ; ventral margin very slightly convex, almost straight 

 in the middle ; superior border sloping rather rapidly downward on both 

 sides of the beaks, which are small, median, incurved and slightly 

 recurved. 



Surface marked with very numerous and closely arranged, minute and 

 concentric raised lines of growth. 



Hinge dentition and anterior muscular impression unknown ; posterior 

 muscular impression narrowly elongate, lanceolate subovate, widest below 

 and acutely pointed above. 



The specimen figured is not sufficiently perfect to admit of very accurate 

 measurements being given, but the figure is of the natural size. 



Nanaimo River, V.I., J. Richai'dson, 1875 : an imperfect but well pre- 

 served cast of the interior of both valves, with part of the test preserved 

 upon each. 



Judging by the figure on Plate 23 of the first volume of the Palaeon- 

 tology of California, the true T. Matheiosoni is more elongate, more 

 pointed at both ends, and consequently more nearly triangular in outline. 



AsAPHis MULTicosTATA, Gabb. 



Asaph is multicostata, Gabb. 1869. Geol. Surv. Calif., Palasont. , vol. i, pp. 181 and 236, 



pi. 29, fig. 70. 

 Linearia Suciensis, Whiteaves. 1879. This volume, pt. 2, p. 146, pi. 17, fig. 12. 



Sucia Islands, J. Richardson, 1875 : the type of L. Suciensis. Na- 

 naimo mines, V. I., W. Harvey, 1901 : a small left valve. 



In a report upon the Cretaceous fossils from Spanish Gulch, Oregon, 

 published in 1901, in Professor J. C. Merriam's " Contribution to the 

 Geology of the John Day Basin," Dr. Stanton writes that L. Suciensis is 

 " similar in form and sculpture " to Asaphis multicostata, "and may be 

 based upon the same species." And, still more recently, a direct compar- 

 ison of L. Suciensis with two authentic Oregon specimens of A. multicos- 

 tata, kindly forwarded by Dr. Stanton, has induced the writer to come to 

 the same conclusion. 



Meretrix nitida, Gabb. 



Cylherea Leonensis, Etheridge. 1861. In Hector's paper in the Quart. Journ. Geol. Soc. 



Lend., vol. XVII, p. 432 ; but not C. Leonensis, Conrad, 1859. 

 Ctitherca Conensis (err. typ. for Leonensis) Etheridge. 1863. No. 42 of the list of speci- 

 mens on p. 243 of Capt. Palliser's Official Report. 



