296 (lARBONlFEKOirS b'OKMATIONS AND FAUNAS OF COLORADO. 



borne in mind tliat this character is often very obscure la the latter as well. A sim- 

 ilar resemblance seems to exist also with Sp. clarksvillensis, but that species, too, 

 has never been fiu'ui'ed and is little known. Spiriferina kentuckyensis approaches 

 this Colorado form in many ways. It diliers in being usually smaller and nmch 

 more nuicronate. The plications and intervening- grooves are slightl}' sharper and 

 the concentric lamella? a trifle finer. But the most marked and constant character 

 is the extended and often mucronate hinge line. 



This form seems at first to be the same as that from the Leadville I'egion 

 described as Sph^ifer sp. b, but a closer examination removes any question of their 

 identity. In their internal structure as well as in the details of their surface orna- 

 mentation they-are quite distinct. 



Locality and Jwrizon. — San Juan region (stations 23Y9, 2381, 2882, 238.5); Ouray 

 limestone. Canyon (station 2366); Millsap limestone. Pikes Peak quadrangle 

 (station 2371); Millsap limestone. Castle Rock quadrangle (stations 2367, 2389); 

 Millsap limestone. 



SEMINULA McCoy, 181-1. emend. Hall and Clarke, 1893. 

 Semintila claytoni Hall and Whitfield. 



1877. Athyris dm/ion!. Hall and Whitfield, U. S. Geol. Expl. 40th Par., Rept., vol. 4, p. 256, pi. 4, figs. 



15-17. 

 Lower Carboniferous limestone (Waverly'?): Little Cottonwood, 800 feet east of Reed and 



Benson's min6, Wasatch Range, Utah. 

 1897. Seminula claytoni. Sehuchert, U. S. Geol. Surv., Bull. "No. 87, p. 378. 



From the vicinity of Salida (loc. 2361) several specimens of Seminula ha,ve been 

 collected. They seem to have been abundant, and, so far as their crushed condition 

 admits the forming of a conclusion, can be referred to S. claytoni White. They 

 appear to represent one of the large oval forms with little or no fold and sinus, and 

 resemble also the species which I described from the Madison limestone as Semmula 

 irnmatura. 8. claytoni is larger than S. immatura and with a less distinct sinus. 

 In these particulars the Colorado material is nearer the former than the latter species. 



*S'. claytoni, occurs associated with Sp. centronatus and probably belongs to the 

 same fauna of which 8. immatura is a member. I rather look to see the two species 

 proved synonymous, but it seems better to await more conclusive evidence before 

 abandoning the latter name. 



Locality and liorizon. — Salida region (station 2361); Leadville limestone. 



Seminula subquadeata Hall?. 



PI. I, fig. 5. 



1858. Athyris suhquadrala. Hall, CTeol. Surv. Iowa, vol. 1, pt. 2, p. 703, pi. 27, figs.2a-d; p. 708, fig. 118. 

 Kaskaskia limestone: Chester, 111.; Crittenden County, Ky. 



