1888.] NATURAL SCIENCES OF PHILADELPHIA. 233 



Aviculopecfen neglectus Meek and Wortlien, 1873. Geol. 111., 

 • vol. V, p. 589. 



The specimens referred to this species are somewhat larger than 

 either of those figured by Geinitz, or Meek and Worthen, but other- 

 wise correspond in every particular. It is without ornamentation 

 excepting concentric lines of growth and the folds or wrinkles of 

 the ear. 



Nuculana bellistriata Stevens. 



Leda bellistriata Stevens, 1858. Am. Jour. Sci., 2nd series, vol. 



XXV, p. 261. 

 Nuculana bellistriata White, 1884. Geol. Kep. Ind. for 1883, p. 



146. 

 At Des Moines this species is not common; but in the black 

 shales oyerlying the workable coal seams at Van Meter in Dallas 

 county it is very abundant, often being found in " nests " closely 

 packed together. 



ITucula parva McChesney. 



NuGula parva McChesney, 1860. Disc. New False. Foss., p. 54. 



Nucula parva Meek and Worthen, 1873. Geol. 111., vol. V, p. . 

 589. 



Giant mine ; quite rare. Owing to its small size it might easily 

 escape notice and this fact may partly account for the apjiarent 

 rarity of this sj^ecies. 



Nucula ventricosa Hall. 



Nucula ventricosa Hall, 1858. Geol. Iowa, vol. I, pt. ii, p, 716. 



Nucula ventricosa White, 1884. Geol. Kep. Ind. for 1883, p. 146. 



Many of the specimens collected exhibit the internal characters of 

 the shell — the characteristic and well defined muscular impressions, 

 and the small prominent teeth along the hinge line. 



Schizodus (sp. und.) 



This genus is represented by casts which occur in nodules of iron 

 pyrites, but the specific characters have not as yet been made out. 

 Clinopistha radiata Hall. 



Edmondiaf radiata Hall, 1858. Geol. Iowa, vol. I, p. 716. 



Clinopistha radiata Meek and Worthen, 1870. Proc. Acad. Nat. 

 Sci. Phila., p. 44. 



Some of the Des Moines specimens exhibit no radiating strise 

 \Thatever,*though the concentric lines of growth are often quite con- 

 spicuous. Inasmuch as the smooth forms and those having distinct 

 16 



