304 EEPOET UNITED STATES GEOLOGICAL SUEYEY. 



This species seems to be at least as distinct from any of other pub- 

 lished forms as they are from each other, but specific variation in this 

 genus is evidently very great. Indeed, I think one cannot examine the 

 original types of the pnbhshed species and the collections subsequently 

 made, together with the original descriptions and illustrations given by 

 Mr. Meek in the publications of the United States Geological Survey of 

 the Territories, without entertaining serious doubts whether more than 

 two or three out of the seven published species of this genus from the 

 Cretaceous strata of the United States are well founded. It is also a 

 fact worthy of note in this connection that all the American species 

 hitherto published are from the same or nearly the same stratigraphical 

 horizon. 



Genus ACT^OK Montfort. 

 Action woosteei (sp. nov). 



Plate 7, figs. 9 a, h, and c. 



Shell small, narrowly subovate ; spire acute, moderately produced, but 

 forming only about one-quarter of the length of the shell ; sides of the spire 

 little if any convex; spiral angle about 50°; volutions five or six, mod- 

 erately convex, the last one not disproportionately inflated ; suture dis- 

 tinct, the distal side of the volutions bending more abruptly into it than 

 the x)roximal side; aperture narrow, distal end acutely angular, proximal 

 end rounded and slightly subangular at the end of the columella ; outer 

 hp thin ; inner lip a little thickened, especially along the proximal half 

 of its length, upon which is apparently the moderately raised fold which 

 characterizes the genus, but the condition of the only examples discov- 

 ered do not show this feature clearly. Surface marked by numerous 

 fine revolving lines, each alternate one being generally a little stronger 

 than the other, but they are apparently otherwise of uniform size upon 

 all iiortions of the surface. The examples are not in a condition to show 

 whether these lines are jjunctate or not, but they probably were, as is 

 usual in species of this genus. 



Length, 13 millimeters ; diameter, 6 millimeters ; length of aperture, 

 7J millimeters. 



The only two examples of this species discovered were in the form of 

 casts of the interior and partial molds of the exterior. The shells also 

 are a httle narrower than typical forms of Actceon, but the observable 

 characters leave little doubt that the species is properly referable to that 

 genus. It differs from A. attenuatus Meek & Hayden, from the Upper 

 Missouri Eiver country, in its much shorter spire, the lesser flattening 

 of the sides of its volutions, especially the body one, and in the propor- 

 tionally longer aperture. From Solidula [Actceonf] riddelU Shumard, 

 from Texas (Proc. Bost. Soc. E"at. Hist., vol. viii, p. 194), it differs in the 

 greater convexity of the spiral angle and in the much coarser and smaller 

 number of revolving striae. The specific name is given in honor of Mr. 

 L. C. Wooster, to whom the Survey is indebted for the opportunity to 

 examine interesting collections of fossils from Colorado, among which 

 were fragments of this species. 



Position and locality. — ^Fox HiUs Group, Cretaceous ; near the conflu- 

 ence of the Saint Trains and South Platte Elvers, Northern Colorado, 

 and also from the Eio San Juan, Southwestern Colorado. Collected by 

 Mr. W. H. HolmeSj artist and geologist of the Survey. 



