126 
Length 17-8 mm., diameter 10-0 mm. 
Melampus clarki White 1 is smaller, more slender, and has a less pro- 
nounced shoulder. Rhytophorus glaber Whiteaves 2 is larger and more 
fusiform. 
Horizon and Locality. Very rare in talus of large concretions from near 
base of Dunvegan sandstone, west bank Smoky river, about 5 miles below 
mouth of Racing creek. 
Type. Victoria Memorial Museum; holotype, Cat. No. 6192. 
Prionotropis caurinus n. sp. 
(' Caurus , the northwest wind) 
Plate XXIII, figures 6, 7 
The specimen figured and the only known specimen, is chiefly a 
mould of the interior. Entirely septate, the living chamber not preserved. 
Of moderate size, gently embracing, the whorl suture a little outside 
the inner row of peripheral tubercles. About four, fairly rapidly enlarging 
whorls. Umbilicus wide, stepped. Whorl section semiquadrate, a little 
higher than thick. Periphery keeled, fairly wide, and somewhat convex. 
Umbilical areas very narrow, somewhat rounded, and at right angles to 
plane of symmetry of shell. 
Costae straight, radiate, numbering about 14 on last whorl (more 
numerous on inner whorls), are progressively more distantly spaced with 
increase in size of whorl. Near umbilical border the costae are raised and 
thickened into an incipient transverse node. Near the peripheral border 
there is an inner rounded node and an outer elongate narrow node nearly 
parallel to the keel. The keel is very small in proportion to the size of the 
shell and gently undulate. 
Height of external lobe about twice its width; about as wide below 
as above; divided by a small saddle. External saddle about as high as 
wide and the width about twice that of the external lobe; divided by a 
small lobule into two nearly equal branches. First lateral lobe a little 
wider than external lobe, but not so deep. First lateral saddle a little 
higher than external saddle. Second lateral lobe very shallow. 
Diameter 58-0 mm. 
Height of whorl 
Thickness of whorl 
Width umbilicus. . . 
The nearest species in the American Coloradoan is Prinoiropis hyatti 
Stanton,® from which it differs in the slightly greater involution of the 
whorls, the more rapid enlargement of the whorls, the smaller keel, the 
different ornamentation, including smaller tubercles, and the different 
suture line. 
Horizon and Locality. Fresh talus of Kaskapau shale, cliff on east bank 
of Smoky river just above mouth of Little Smoky river; estimated from 
about 200 feet above base of Kaskapau shale member. 
Type. Victoria Memorial Museum; holotype, Cat. No. 6193. 
iW. S. G. s. ( Bull. 128, 1895, p. 42, PL 5, figs. 2, 3. 
1 Cant Can. Pa)., 1, pt. 1, 1885, pp. 69, 70, Pi. 10, figs. 4, 4arO. 
« U.S. Geol. Surv., Bull. 106, 1893, p. 176, PI. 42, figs. 5-8. 
