130 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [btju.108. 



the Cretaceous section at Coalville, Utah, and in equivalent beds at Bear 

 Biver city, Wyoming. Neritina carditoides, which is a closely related 

 but probably distinct species, occurs at a much higher horizon in the 

 u third ridge" of the same section. 



TURRITELLID^E. 

 Genus TUERITELLA Lamarck. 



TURRITELLA WHITEI n. Sp. 



PI. xxviii, Figs. 12-16. 



Turritella uvasana White, 1876, U. S. Geog. and Geol. Sur. West 100th Meridian, vol. 



iv, p. 195, PI. 18, Figs. 11a and b. 

 Not Turritella uvasana Conrad, 1856, Pacific Railroad Repts. vol. v., p. 321. 



This species was first obtained from Cretaceous strata southeast of 

 Paria, Utah, and was doubtfully referred to Turritella uvasana, a spe- 

 cies of the Tejon formation of California. 



Dr. White describes the Utah specimens as follows : 



"Shell of ordinary size, elongate, slender ; sides straight; volutions 

 numerous, apparently reaching eighteen or twenty when full-grown ; 

 the sides of the volutions nearly straight or only slightly convex; 

 suture broad, deeply impressed. 



" Surface marked by numerous revolving raised lines, six or eight of 

 which are moderately large, the smaller ones alternating with them. 

 The larger lines are minutely nodose upon the larger volutions, and 

 upon the last one they are even subspinulose. 



u All the specimens of this species in the collection are more or less 

 broken, but judging from the apical angle indicated by their sides, the 

 largest must have been about 5£ centimeters long, and its last whorl 

 about 13 millimeters in diameter." 



Since the above description was published. Mr. C. D. Walcott has col- 

 lected a number of good specimens at Upper Kanab, Utah, and the 

 writer has more recently obtained a great many from the Pugnellus sand- 

 stone of Huerfano park, Colorado. The study of this additional and better 

 material has proved that it differs from Conrad's species in several par- 

 ticulars. The revolving lines of Turritella uvasana are not nodose, the 

 apical angle is less than in our species, and the whorls are broader, so 

 that there is a less number of volutions in a given length of specimens 

 of the same size, and it is probable that the total number of volutions is 

 less in the California species. Some young specimens of T. whitei (or 

 tips of old ones) from Upper Kanab have about twenty volutions in a 

 length of a little over half an inch, and the diameter of the last whorl is 

 only 3 millimeters, or about the same as the upper end of the specimen 

 represented by Fig. 12 on PI. xxviii. An individual of that size would,, 

 therefore, have about thirty volutions when complete. 



