420 CARBONTFKKOUS FOKMATroNS ANO FAUNAS OK COLORADO. 



MODIOLA Ivuiuuirk, 1801. 



MODIOT,A? SUBKT,I.Tl-nCA Mcck. 



1860. ('lidiipliiiriia (iiu J'Icnroplionts) occiiloila/is. Geiiiliz Carli. uiid Dyiis in Nebraska, ]i. 23, tal). 2 

 fig. 6. (Not Pleurophorus occidentalisM. & H., 1858.) 



l^ppci- Coal Pleasures: Nebraska City, Nebr. 

 1872. Modiola? subclliplica. Meek, U. S. Geol. Surv. Nebraska, p. 211, pi. 10, Jig. 5. 



Upper Coal Measures: Nebraska City, Nebr.; Riverside, 3 miles below Atohison, Kans. 

 1881. Pleiirophoriis subcostaiits. AVhite, TJ. S. Geog. Geol. Surv. W. lOOtb Mer., Kept., vol. 3, Supp., 

 Appendix, p. xxvii, pi. 3, fig. 8. 



Carboniferous: Coyote Greek, New Mexico. 

 1900. ModioJd niibelliptica. Beede, Univ. Geol. Surv. Kansas, Kept., \'ol. 6, p. 136. 



Upper Coal ^Measures: Topeka, Kans. 



This form is represented by onl}^ two specimens found eacli at a diffei'ent 

 locality. It is probable that it does not belong, strictly sjDeaking, to the genus 

 ModioJa, but it is so thin and delicate that characters of hinge and muscle scars are 

 not shown. 



The form from New Mexico which White identifies with Pleuropliorua siihcos- 

 tatus I am convinced, from a direct comparison of specimens, belongs with this 

 species. 



Locality and horizon. — San Juan region (stations 2221, 2233); upper poi'tion of 

 the Hermosa formation. 



MYALINA de Koninck, 1814. 



Mtalina cuNEiFORMis Gurley. 



PI. VIII, figs. 14-17. 



1883. Myalma mndformu. Gurley, New Carb. Foss., Bull. No. 1, p. 4. 

 Upper Carboniferous: Ouray, Colo. 



Through the courtesA^ of the geological department of the University of Chicago, 

 1 have been enabled to examine the type specimens of Mycdina cuneiformis and to 

 illustrate the species partially from Gurley's original material. 



The original description of M. cuneifm'mis is given in the following terms: 



" Shell small, nearl}^ or quite equivalve, long, narrow, attenuated with prominent 

 straight subangular umbonal ridge extending from the small, sharp-i3ointed terminal 

 beaks across the shell to the posterior basal margin, attaining its greatest prominence 

 about one-fourth of the length of the shell from the lieaks, where the thickness of 

 the shell is equal to two-thirds its greatest width. 



"Cardinal margin nearly straight, extending almost half the length of the shell 

 and o-racefuU}^ curving into the posterior margin, which is slightly flattened and 

 oblique, regularly rounding down and around, joining the anterior basal margin just 



