318 CABBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 



1887. l<\itsHVniii ciilindrim. Herrick, Sri. Lab. Peiiison Univ., Bull., vol. 2, p. hi), jil. :!, li};. 20. 



Coal Measures: Flint Ridge, Ohio. 

 1891. FitmHiKi ci/lindrica. Keyes, Acad. Nat. Sci. Philadelphia, rroc, p. 245. 



Lower Coal Measures: Des Moines, Iowa. 

 1894. Fii.tulimi nilindrica. Keyes, Missouri Geol. Surv., vol, 4, ji. 102, pi. 12, ligs. 1 <i-c. 



Coal Measures: Kansas City and Lexington, ^lo. 



1899. PusMlina eylindrica. Smith, Kansas Acad. Sci., Trans., vol. Ki, p. 64, figs. 1-4. 



1900. FnsuliiM xccalica. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, j). 10, ]il. 1, figs. 1, Ih. 

 Upper Coal Measures: Kansas. 



'The genus Fvsulma expei'ienced a long range in the Carboniferous strata of Colo- 

 rado, although it i.s possibly less abundant at the lower horizons than at the upper. 



The lowest ascertained occurrence of the genus is at Ouray, where it is plentiful 

 at an horizon about 100 feet above some beds with fossil plants, the evidence of 

 which, though not conclusive, would favor correlating them with the lower portion 

 of the Lower Coal Measures as developed in the Pennsylvania section. In the San 

 Juan region also FusuUna is found toward the base, as well as near the top, of the 

 Carboniferous section, and a range probably of 2,000 feet must be assigned to it in 

 this area. A similar range is indicated by its occurrence at Leadville. 



It is difficult to correctly estimate the shape and size of these small bodies, as 

 they lie promiscuously diffused through the rock in which thej^ are embedded, but 

 examples from the same locality seem to be in essential agreement with each other 

 in the particulars named, while, with the exception of a station in the Crested Butte 

 region (2312), all the occurrences noted appear to belong to the same species. This 

 opinion, however, is based upon their agreement in external characters and lacks the 

 corroboration of microscopic studj-." 



The pi'evailing form in the Coloi'ado collections is rather small and spindle shaped, 

 with an axial diameter of from 3 to i mm. and a radial diameter of from 1.5 to 2 mm. 

 While there seems to be but little variation in F. eylindrica as it appears at differ- 

 ent localities, specimens from the San Juan region often attain a larger size than 

 elsewhere. 



It is doubtless ti'ue that wherever this species has been found it is abundant, 

 but this circumstance probablj^ proceeds from the fact that owing to its minute size 

 it attracts attention only when present in large numbers. But if its rarer occur- 

 rences were known it would perhaps be found to be rather continuously represented 

 in the rocks than, as seems now, at remote but prolific intervals. 



Beede employs the name Fimulina secalica instead of the more familiar one 

 proposed by Fischer, the specific portion of the combination being due to Sa^'. The 

 latter originally referred his types, which were obtained on the Missouri River near 

 the Platte, to Miliolites, but it is clear that he had a species of Fiisulina. In view 



« Microscopic study of these shells, as far as it has been carried by me, tends to confirm the opinion that they belong 

 to one species. 



