NO. 12 SPENCE SHALE AND ITS FAUNA RESSER 7 



GASTROPODA 



HYOLITHES Eichwald, 1840 

 HYOLITHES CECROPS Walcott 



Plate I, figs. 36-38 



HyoUthcs cccrops Walcott, Smithsonian Misc. Coll., vol. 67, no. 2, p. 27, 



pi. 5, figs. 3-3C, 1917. 

 HyoUthcs idahociisis Resser, idem, vol. 97, no. 3, p. 5, pi. i, figs. 57, 58, 1938. 



This is an abundant species, but owing to its large size and shale 

 matrix, few complete specimens are available. Numerous operculae 

 are preserved. Assembly of many specimens shows that the Spence 

 shale form, together with that in the Rennie shale, is identical with the 

 Ross Lake shale species. 



Ross Lake; (loc. 63J) Popes Peak, i^ miles south of Stephen, and 

 other localities, British Columbia. 



Rennie; (loc. 37m) North Gold Creek, Pend Oreille Lake. 



Spence ; localities 55c, 55e, and 54L. 



Cotypcs. — U.S.N.M. no. 63724; plesiotypes, nos. 95021, 96496. 



HYOLITHES ORNATELLUS, n. sp. 



Plate I, figs. 30-32 



This is the most highly ornamented species of HyoUthcs known. 

 The anterior side is flat and depressed below the rounded margins, 

 while the posterior surface is arched. Strong striations run at right 

 angles to the axis on the anterior surface, but on the posterior are 

 parallel with the front margin. 



Locality 55c. 



Cotypes. — U.S.N.JVI. no. 96494. 



"ORTHOTHECA" SOLA, n. sp. 



Plate I, fig. 2,2, 



A single conical tube was found among the thousands of Spence 

 shale fossils. This shell has nearly a circular cross-section and is 

 about 8 mm long and 4 min wide at the aperture. 



Locality 55c. 



Holotypc. — U.S.N.M. no. 96495. 



