456 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 



Phanerotrema sp. 



Near Glenwood Springs, at station 2193, a small collGction was obtained which 

 indicates the presence at that place of an interestinu- and extensive fauna. The 

 fossils are chiefly gastropods and are of very minute size. As I have indicated, the 

 fauna, if carefuUj' collected, would probably prove an extensive one. It would also 

 be dithcult to study. As the entire shell is very small, tlie surface ornamentation is 

 almost microscopic, and, unless well pi-eserved, can not satisfactorily be made out. 

 Fortunately the preservation at this locality is generally good. I have discriminated 

 about six species in the material collected and suspect that there may be several 

 others. Without doubt these represent only a small proportion of the entire fauna. 

 1 have found it sufficiently difficult to arrive at approximate determinations of 

 these species, to believe that many of them are new. No new names have been pro- 

 posed, however, because it seems that a miniature fauna, such as this is, should be 

 studied onlj' from especially abundant and especially pei'fect material. 



One of the most abundant types among the gasteropods is a little Phanerotrema 

 which is related to PA. grayvillense and Ph. constrictum. Many species of this group 

 have been considered, but none with which this can be satisfactorily identified. 

 The height is between 3 and 4 mm., and the diameter nearly the same. The 

 height of the spire is 2 mm., or a little over. There are about 4 volutions. The 

 lower portion of the outer whorl is marked by a number of comparatively large 

 strife, which also transgress upon the flattened periphery. This striated portion is 

 succeeded by a broad, flat slitband whose direction is neaidj- vertical. Above the 

 slitband is a carina which constitutes the most prominent jjortion of the entire 

 peritreme. It is probably somewhat nodose. The upper portion of the peritreme 

 declines from the vertical by an angle of about 45°. It is slightly concave and 

 appears to be without ornamentation. Just below the suture is a row of small nodes 

 or possibly a nodose revolving i-idge. Most of the strife marking the lower portion 

 of the peritreme are of course covered over by the succeeding volution, but a few 

 of the upper ones are left exposed. 



Locality. — Grand River region, Glenwood Springs (station 2193). 



WOETHENIA de Koninck, 1883. 



WORTHENIA TABIILATA Conrad? 



1835. Turho labulata. Conrad, Geol. Soc. Pennsylvania, Trans., vol. 1, pt. 2, p. 267, pi. 12, fig. 1. 

 1842. Pleuroiomaria iabulata. Conrad, Acad., Nat. Sci. Philadelphia, Jour., (1), vol. 8, p. 272. 



Carboniferous: Inclined plane of the Allegheny Mountains. 

 1858. Pleuroiomaria tabulata. Hall, Geol. Surv. Iowa, vol. 1, pt. 2, p. 721, pi. 29, figs. 12a, b. 



Coal Measures: Pennsylvania, Indiana, and Illinois. 

 1881. Pleuroiomaria labulaia. AVhite, Dept. Stat, and Geol. Indiana, 2d Ann. Rept., p. 519, pi. 18, figs. 

 4,5. 



Coal Measures: Rush Creek, Posey County, Ind. 



