1888.] NATURAL SCIENCES OF PHILADELPHIA. 243 



Nautilus (TemnocJieilus') winslovi Meek and Wortlien, 1873. 



Geol. Ill, vol. V, p. 609. 

 Nautilus ivinslovi White, 1884. Geol. Ind., Kept, for 1883, p. 



165. 

 Not common, and usually fragmentary. 



CRUSTACEA. 



Cythere nebracensis Geinitz. ? 



Cythere nebracensis Geinitz, 1866. Carb. und Dyas in Nebraska, 

 p. 2. 



It is with some doubt that the form from Des Moines is referred 

 to Geinitz's species ; it is much smaller than that Avhich he described, 

 and also differs in other particulars. A dozen or more good speci- 

 mens were collected at the Pioneer mine where they were associated 

 with Synocladia biserialit. This and a trilobite are the only crusta- 

 cean remains thus far discovered in the carboniferous strata at Des 

 Moines. The remains of articulates in the lower coal measures of 

 Iowa are exceedingly rare, and the only hitherto known specimens 

 of this group are more or less fragmentary remains of a single genus 

 of trilobites. Prior to this, ostracoid crustaceans have been collected 

 in Iowa in the upper and middle coal measures, and now is recorded 

 their presence in the strata of the lower coal measures of the state. 



Phillipsia (sp. ?) 



Of the trilobites only a single pygidium of a Phillipsia has been 

 collected, and this at the Pioneer mine. 



VERTEBRATA. 



Petrodus occidentalis Newberry and Worthen. 



Petrodus occidentalis Newberry and Worthen, 1866. Geol. 111. 

 vol. Ill, p. 70. 



From the Pioneer mine have been collected nearly all the remains 

 of fishes that have been found in the carboniferous strata of this re- 

 gion. It is with some little doubt that the dermal tubercles that are 

 here referred to this species really belong to it. The base is subquad- 

 rate in outline; and the thin abruptly sharpened edge is broader 

 than in the one figured by Newberry and Worthen ; the ridges ex- 

 tending downward towards the obtuse angles of the base are much 

 more prominent than the others, which do not extend to the top of 

 the crown. There has also been collected at this mine the fin spines 

 of two species ; one about two centimeters, and the other four centi- 



