DESUKimoNS OF SPECIES. 281 



1899. Productella cooperensis. Girty, U. S. Geo]. Surv., Mon., vol. 32, pt. 2, p. 528, pi. 68, tigs. 8a-8f, 

 9a, 9b. 



Madison limestone: Yellowstone IS^ational Park. ' 



1901. Productella concentrica. Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 184, pi. 16, figs. 12-14. 



Kinderhook: Bed 6, Burlington, Iowa. 



There are but two specimens in our collections from Colorado which represent 

 this species, both of them small and imperfect. Thej are not referred without reser- 

 vation to Productella concentrica, for lack of conclusive evidence, but at the same time 

 I know of no reason for mistrusting the identification. 



In discussing the synonymy of this species in 1896 I expressed the opinion that 

 Productellco slmmardiancc and P. ccmcentrlca are distinct, but that the former is prob- 

 abh' identical with P. ■pyxidata. Some ambiguity is probably introduced into this 

 utterance, and into those of Winchell and Herrick as well, from the fact that under 

 the name Productus shumardlanus two species wei'e probablv included bj^ Hall. One 

 of these is represented b}^ figure 9 of plate 3 among the Hamilton fossils and the 

 other by figure 2 of plate 7 among those of Chemung age. The former was obtained 

 from Clarksville, Mo., and the latter from Burlington, Iowa. It matters not that 

 Hall was in error in regard to the age of these fossils. They came from verj'- difl:er- 

 ent localities and from somewhat different horizons. In the case that these two forms 

 thus differenth' derived are, as an inspection of the figures would lead one to believe, 

 specifically different, I propose to restrict the name P. sJtumardiana, to the Clarks- 

 ville form, which is the first figured in the plates and the first mentioned in the text. 

 With the disposition of P. sludnardlana, whether it is retained as a distinct form or 

 is placed in the synonymy of P. pyxidatcc or of P. subalata, I am not nqw concerned. 

 I believe, however, that the Burlington form of P. sJiumardktna is only a dorsal valve 

 of a species which is described from the same jslace under the name of P. concentrica. 

 This conclusion is one which can be absolutely vindicated only hj a comparison of 

 the types themselves. The collateral evidence, however, seems to me all but con- 

 vincing, since in one case we have specimens from different localities and different 

 horizons which excellent figures show to be different and in the other specimens from 

 the same locality and the same horizon which excellent figures show to be the same. 



The opinion is still entertained that P. cooperensis is a synonym for P. concentrica 

 and that WinchelPs identification of it from Sciotoville is based upon a distinct though 

 related species. 



Locality and horizcni. — San Juan region (station 2379); Ouray limestone. 



