DESCRIPTIONS OF SPECIES. 419 



ENTOLIUM Meek, 1865. 

 Entolium? sp. 



There is only one specimen representing this species. It is too poor for deter- 

 mination, and is considered here onl}- because it seems to form the basis for the 

 identification which is recorded in the faunal list of the Leadville monograph." 



Locality and AoWswi.— LeadvUle district (station 2275); upper portion of the 

 Weber formation. 



STREBLOPTERIA McCoy. 1851. 



Steeblopteria tenuilineata Meek and Worthen. 



I860. Pecten ienmlineatus. Meek and Worthen, Acad. Xat. Sci. Philadelphia, Proc, p. 452. 



Upper Coal Measures: South line of Clinton County, 111. 

 1866. Strehlopteria^ tenuilineata. Meek and Worthen, Geol. Surv. Illinois, Eept., vol. 2, p. 3.34, pi. 26, 

 figs. 9a, b. 

 . Upper Coal Measures: South line of Clinton County, 111. 



We have this species from three localities, but it is represented by only a single 

 specimen at each. The material is fragmentarj' as well as scanty, so that it is identi- 

 fied with some doubt. The surface appears to be the same in all, but is best shown 

 bj' the example from station 2221 (Rico quadrangle, Sandstone Mountain), which is 

 as to other characters very imperfect. Even with a glass only faint concentric .striae 

 can be made out, which partake rather of the nature of growth lines than of orna- 

 mentation. A small area on the specimen from Ouray (station 2195b) shows very 

 fine radiating stria?, which may be due to shell structure, or possibly to mineraliza- 

 tion. The largest and mo.st perfect specimen is that last mentioned. In size and 

 configuration it closely resembles the right valve of Streblojpteria tenidUneata. The 

 anterior ear, however, shows .some faint markings which might be interpreted as ribs 

 if it could he shown that they are not accidental. This character rather suggests the 

 form EucJiondria neglecta Geinitz, but the shape is not right for that species. A 

 smaller somewhat less perfect example from station 3216 (Rico quadrangle. Sand- 

 stone Mountain) has the shape of the larger one just mentioned, but the anterior ear 

 is clearly seen to be marked with rather lamellose concentric stri^ without a trace of 

 ribs. I am not confident, owing to the fragmentary character of one of the speci- 

 mens that all three belong to the .same species, but those from stations 2216 and 2195b 

 are probably conspecific with each other and with the species cited above. 



Locality and Iwrizon. — San Juan region (stations 2216, 2221) ;• upper portion of 

 the Hermosa formation. Ouray (station 2195b); Hermo.sa formation. 



a U. S. Geol. .Surv., Mon., vol. 12, 1886, p. 70. 



