Weller — Kinderhook Faunal Studies. - 



bonal ridge to the dorsal margin, the ventral slope much 

 broader and more gentle, with a shallow sinus extending from 

 the beak obliquely backward to the sinuosity in the ventral 

 margin. Surface marked with more or less regular sublam- 

 ellose, subimbricating, concentric undulations, which are less 

 than one-half millemeter apart upon the umbonal ridge 

 where they are most distant. 



The dimensions of three specimens are: length, 9, 10.5 

 and 12 mm.; width 4.5, 5 and 6 mm.; convexity, 2, 2, and 

 3.5 mm. 



Reinarks. This species is one of the most abundant forms 

 in the Glen Park fauna, innumerable individuals being present 

 throughout the limestone. It resembles C. indenta (Con.) 

 from the Onondago and Hamilton faunas of New York, but 

 differs from that species in the character of its surface mark- 

 ings, none of the fine radiating lines of G. indenta having 

 been observed ; it is also a proportionately narrower shell 

 than that, and never grows so large as the larger individ- 

 uals of the Hamilton species. Other species cogeneric with 

 this species occur in the Waverly faunas of Ohio, in the Kin- 

 derhook at Burlington, Iowa, as well as in the Spergen Hill 

 fauna of Indiana and in the Coal Measures, but the Glen 

 Park species is clearly distinct from all of these. 



GASTROPODA. 



Ptychomphalus MISSOURIEN8IS n. sp. 



Plate 2, figs. 2S-26. 



Description. Shell small, imperforate, with about four 

 volutions, apical angle 70°-80°, the suture impressed, the 

 volutions rounded on the periphery, the aperture subcircular in 

 outline ; slit-band narrow, bounded by slightly elevated costae 

 between which the surface is slightly convex, the elevation of 

 the center of the band being about even with the tops of the 

 bounding: costae. Surface of the shell above the band, 

 marked by transverse costae somewhat stronger toward the 

 suture, which curve backward as they approach the peripheral 

 band, about four or five occupying the space or one mille- 

 meter, this same surface is marked also by somewhat finer 



