DESCRIPTIONS OF SPECIES. 283 



In a report published in 1899 dealing with some Carboniferous fossils from 

 Yellowstone National Park 1 recognized the cosmopolitan species Productus s&ini- 

 reticulatus, several individuals of which were hg'ured. Mention was made that the 

 material thus identified showed a wide range of variation, some of it departing 

 considerabl}' from the type represented hj the figures. These same varieties occur, 

 for the most part, in the limestones of Burlington and Keokuk age in the Mississippi 

 Vallej', and have there been distinguished hj different specific names. The material 

 from the Park, being both scattered, scanty, and often fragmentary, did not lend 

 itself to nice specific discriminations. • Nevertheless, I believe that subdivisions 

 should then have been made. 



The Colorado material is still more imperfect than that from Yellowstone Park, 

 but does not embi-ace as widely divei'gent types. At the same time, I am not confi- 

 dent that two species or varieties may not be present. The same form or forms are 

 found in Yellowstone Park and in the lower Mississippian faunas of the Mississippi 

 Valley. It is doubtful if any of these Mississippian forms, commonly identified with 

 P. semireticulatus, show precise specific identity with the dominant tj'pe of the Upper 

 Carboniferous, and at least there is nothing in the fauna of the Hermosa formation, 

 so far as it ha.s been brought to light, with which a critical comparison would justif}' 

 identifying the fossils which form the subject of these notes. 



In the matter of synonj^my I have brought together all, or at least the most 

 important citations of American Mississippian forms, not so much to imply that 

 thev are all one species, or the same as my Colorado material, but to indicate that, 

 as 1 believe to be the case, these Mississippian forms are distinct from the Pennsj'l- 

 vanian ones. 



Locality and horizon. — San Juan region (stations 2379, 2381, 23S2< 2381:); Ouraj^ 

 limestone. Crested Butte district (station 2351:); Leadville limestone. 



Productus parvifoemis Girty. 



1899. Productus parrifortiiu. Girty, V. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 536, pi. 68, figs. 6a-6d. 

 Madison limestone: Yellowstone National Park. 



At one localitj' in the San Juan region (station 2381) occurs a form in .some 

 abundance which I believe can be safely identified with Productus yarviformis. The 

 only difi'erence which I am able to point out consists in the fact that the individuals 

 from Colorado are apt to be a trifle undersized. 



Locality and liorlzon. — San Juan region (station 2381); Ouray limestone. 



Productus cf . pustulosus Phillips. 



1836. Produclapastulosa. Phillips, Geol. Yorkshire, vol. 2, p. 216, pi. 7, fig. 15. 



Mountain limestone; Bolland; Florence Court. 

 1857. Productus pustulosus. Davidson, Pal. Soc, British Garb. Brach., pt. 5, p. 168, pi. 41, figs. 1-6; 

 pi. 42, figs. 1-4. 



