356 



so nearly resembles it tliat some consider the latter as only a variety 

 of A. suhtilita. 



Locality and ijosition. — Katlaliwoke Creek, just west of the second 

 principal range of the Eocky Mountains : latitude 49° north, longitude 

 114° west : Carboniferous. 



CRETACEOUS SPECIES. 

 LAMELLIBRAIv[CHIATA. 



Genus NUCULA, Lamarck. 

 XucuLA Traskana, Meek. 



Nacula Traslana Meek (1857), Trans. Albany lust., iv, 39. 



Shell trigonal-ovate, with both extremities rather narrowly rounded ; 

 cardinal border sloping from the beaks at an angle of about one hundred 

 degrees; base forming a broad gentle curve; beaks nearly central, 

 rather elevated ; surface unknown; muscular impressions shallow; hinge 

 having in each valve about fifteen teeth on each side of the small pit for 

 the reception of the ligament. 



Length, 0.27 inch ; height, 0.18 inch ; breadth, 0.16 inch. 



The only specimen of this species that I have seen is a cast, which is so 

 much worn as to show imperfectly the surface-characters. As nearly as 

 can be determined, it appears to have been i)rovided with rather dis- 

 tinct concentric lines of growth ; and, judging from a depression along 

 the anterior slope of the cardinal margin, it was probably provided with 

 a "well-defined lunule. The species will probably be recognized by its 

 ventricose trigonal-ovate form, and nearly central beaks. 



Since first describing this species, the only specimen in the collection 

 has been mislaid, so that I am unable to give a figure of it. The spe- 

 cific name w-as given in honor of Dr. John B. Trask, of San Francisco. 



Locality and position. — The specimen came with others labeled 

 "Nauaimo, Vancouver's Island"; though it may have been collected at 

 Komooks. 



Genus GEAMMATODON, Meek. 

 Geaimmatodon ? Vancouverensis, Meek. 



Plate 3, figs. 5 and 5 a. 

 Area Vancouverensis, Meek (1857), Trans. Albany Institute, iv, 40. 



Shell small, longitudinally oblong, moderately gibbous, comparatively 

 thick and strong; anterior margin rounding up from below and meeting 

 the end of the hinge nearly at right angles ; posterior side somewhat 

 obliquely truncated ; base nearly straight and parallel with the hinge ; 

 cardinal area rather narrow; hinge nearly or quite equaling the greatest 

 length of the shell ; beaks located a little in advance of the middle, 

 rather small, and incurved; posterior umbonal slopes prominently 

 rounded from the beaks to the postero-basal margin ; surface orna- 



