620 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



north of old road to Mammoth Hot Springs; Cinnabar Mountain; saddle in 

 ridge west of south branch of Gardiner River; south slope of ridge south 

 of Gray Mountain, and east end of north 3ast spur from Signal Peak. 



ASTARTE MEEKI 11. Sp. 

 PI. LXXIJL figs. 3-5. 



Shell of medium size, subcircular in outline, moderately convex ; beaks 

 prominent, median in position ; dorsal margin descending rapidly from the 

 beaks, with a convex curve behind and slightly excavated in front; anterior, 

 posterior, and ventral margins forming a regular curve ; surface marked hj 

 numerous fine, regular, concentric costa?. Margin crenulate within. 



One of the types, an averag*e-sized specimen, has the following dimen- 

 sions: Length, 16 mm.; height, 14 mm.; convexity of single valve, about 3 

 mm. The largest specimen in the collection is 23 mm. in length and 20 

 mm. in height. Associated with these there are several more elongated 

 shells, one of which is figured, that I was at first inclined to regard as a 

 distinct species, but it is probable that the difference in form is due to dis- 

 tortion by pressure. 



Compared witli Astarte pachardi White this species is proportionally 

 somewhat more elongate, less convex, and the concentric sculpture is much 

 finer and more regular. The species was first noticed by Meek, who men- 

 tioned it as 'Astarte (!)" in a list of Jurassic fossils collected by Dr. Peale 

 near the lower canyon of the Yellowstone. 1 It occurs in the collections 

 from head of Gardiner, Sentinel Butte, Cinnabar Mountain, west side of 

 Snake River north of Berry Creek. 



Astarte sp. 



Another species of Astarte is represented by fragmentary specimens 

 which show the specific features fairly well, but as they are not sufficient 

 for a good illustration the species has not been named. It is a A'ery 

 elongate form, with strong, regular, concentric ridges. In its younger 

 stages, as shown by the lines of growth, it is a short subtriangular form, 

 but later it rapidly increases in length and the posterior end becomes 

 obliquely truncate. It occurs on the divide at head of Fawn Creek, 

 Sentinel Butte, Cinnabar Mountain, and near lower canyon of Yellowstone 

 River. 



Ann. Rept. IT. S. Geol. Surv. Terr, for 1872, p. 172. 



