334 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 



umbilicus, and the lasit one or two free and in-egularly bent. The ci'o.ss section is 

 circular. The surface seems to be marked with regular, very line, transverse 

 strii^, and toward the aperture by a few irregular, transverse wrinkles. Well- 

 preserved surfaces are also seen to be minutely papillose, or occasionally appear as 

 if the crests of the strias were minutel}^ crenulate. 



The data thus briefly set down are derived largely from the material from 

 station 2311. Thoi'igh specimens occur more abundantly at station 2310, the preser- 

 vation is umch less satisfactory. Nevertheless the species is believed to l)e the same 

 at both. 



My material, while attaining a somewhat greater size than that shown by 

 Dawson's figure of Spi/rorhis arietina^ agrees with that species in so manj' particulars 

 as to lead me to believe that if not actually identical with it, it is at least very closely 

 related. 



This form differs from that occurring at Glenwood Springs in being larger- and 

 in appearing to lack the longitudinal stri^ of that species. The latter is also close- 

 coiled throughout and the final portion is not free as in Sp. arietma. At the same time 

 I am not sure that an abundance of good material would show that thejr are distinct. 



Locality and hcuHsori. — Crested Butte district (stations 2310, 2311); Maroon 



formation. 



Spikorbis sp. 



This form occurs in abundance at Glenwood Springs, and in an excellent state of 

 preservation. It forms small, rather regularlj^ conical sinistral shells, consisting of 

 two or three volutions and "having a moderately high spire. The larger specimens 

 have a diameter -of 2 mm. The surface is crossed by numerous delicate transverse 

 striae, and also by fine, wavy, probably inosculating, revolving ones. The tube shows 

 additional irregularities, chieflj^ of a concentric kind, due to growth. The surface 

 ornamentation, though minute, is verj^ prettj^ and very well shown. 



This form is probably distinct from that referred to Sjj. arietina. It is as a rule 

 considerably smaller, and specimens of the latter seem to lack the surface markings 

 of this one, though not being so well preserved that character vaa.j have been obscured 

 in them. 



Locality. — Grand River region, Glenwood Springs (station 2198). 



BRYOZOA. 



FISTULIPORA McCoy, 1849. 



FiSTULIPORA CARBONARIA Ulrich. 



1884. Fistulipora carhonaria. Ulrich, Jour. Cincinnati Soc. Nat. Kist., vol. 7, p. 45, pi. 3, figa. 1, la. 



Upper Coal Measures: Kansas City, Mo. 

 1895. Fistulipora carhonaria. Keyes, Missouri Geol. Surv., vol. 5, p. 16. (Date of imi>rint 1894.) 



Upper Coal Measures: Kansas City, Mo. 



