156 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [bull. 106. 



EOSTELLITES DALLI n. Sp. 



PL xxxiii, Figs. 11-13. 



Shell of medium size, slender fusiform ; spire elevated but not quite 

 equal to the aperture in length 5 volutions about seven, convex, with a 

 narrow constriction below the suture; body whorl large and in some 

 specimens rather ventricose. Surface ornamented by distinct revolv- 

 ing lines and prominent rounded, transverse costae, the latter dying out 

 above the middle of the body whorl. On the last volution there are ten 

 transverse costoe and about twenty revolving lines. Aperture long and 

 narrow, with a slight notch at the posterior end as indicated by the 

 lines of growth; outer lip lirate within; inner lip with a thin deposit of 

 callus. Pillar nearly straight, with three distinct oblique folds near the 

 middle, the anterior fold being the stronger. The folds are scarcely 

 visible in the aperture view of an unbroken specimen. 



Length of a medium sized specimen, about 80 mm ; greatest breadth, 

 25 mra . Other specimens are considerably broader in proportion to their 

 length. 



The apex is not preserved in any of the specimens so that the char- 

 acter of the nucleus has not been determined. 



This species seems to be congeneric with Bostellites texanus Conrad, 

 which is the type of the genus to which Gabb subsequently gave the 

 name Volutoderma. Specificially it is closely related to Voluta {Bos- 

 tellites) elongata d'Orb., which, occurs in the Turonian of Prance, the 

 Gosau beds of Austria, and the Arrialoor and Trichinopoly groups of 

 southern India. 



Internal casts are not easily distinguished from the following species 

 with which it is associated, but the surface ornamentation is very dif- 

 ferent. 



Localities and position. — In the Pugnellus sandstone at many locali- 

 ties in Huerfano park, and at a slightly lower horizon on the Arkansas 

 river, 20 miles above Pueblo, Colorado. 



EOSTELLITES AMBIGUA n. sp. 



PI. xxxiii, Figs. 8-10. 



Shell of rather large size, spindle shaped; spire elevated and rather 

 slender, somewhat more than half the length of the aperture; whorls 

 about seven in number, moderately convex, the last one very large; 

 suture distinct, more or less channeled. Below the rounded border of 

 the suture the whorl is slightly constricted or flattened. Surface orna- 

 mented by numerous closely arranged revolving lines and by larger 

 curved transverse costse that are less conspicuous on the body whorl 

 than on the spire, and that have a tendency to form nodes just below 

 the suture. 



The aperture is narrow, prolonged into the rather short canal, and 

 with a short posterior notch. Outer lip thin, obscurely lirate within, 



