PELECYPODA. 113 



1901. Conocardium ohioense Kindle, 25th Ann. Report Indiana Dept. Geol. Nat. Res., 



pp. 686-687, pi. 15, fig. 7. 

 1909. Conocardium ohioense Grabau and Shinier, North American Index Fossils, I, 



p. 438, fig. 575. 

 1911. Conocardium ohioensis? Cleland, Wisconsin Geol. Nat. Hist. Surv., Bull. 21, p. 



109, pi. 21, figs. 7, 8. 

 Hall's description — "Shell small, ovate, subtrigonal, ventricose behind the middle 

 of its length; length one-third greater than the height. Posterior end prominent, 

 produced in the middle and sloping abruptly to the post -cardinal angle. Anterior end 

 abruptly contracted in front of the middle and prolonged, nasute, with the extremity 

 narrowly rounded. The body of the shell is marked by about six strong radiating plica- 

 tions on the ventricoss portion of the value, and on each side more numerous and 

 smaller plications. The interspaces between the libs are marked by lamellose concentric 

 striae. A specimen of this species has a length of 15 mm. and a height of 10 mm. This 

 species differs from C. cuneus in being more narrowly -ventricose, and the body of the 

 shell marked by fewer plications, with a distinct constriction in front; the umbonal 

 slope is more rounded and less oblique, while the posterior extremity is more produced 

 than in the usual forms of C. cuneus and C. trigonale." 



Remarks — This species is abundant in the Mineola of Montgomery and Ralls 

 Counties, and has been collected from the Callaway of Moniteau County. The speci- 

 mens are small and display considerable variations. Most of the specimens 

 show about six strong plications and all others much smaller but in some speci- 

 mens the plications are nearly equal in size. Ordinarily the plications on the anterior 

 slope of the ventricose part are the stronger but on some specimens those on the posterior 

 slope are larger than on the anterior. Commonly a longitudinal groove marks or divides 

 each plication but some specimens have simple plications. Commonly the anterior end 

 projects to form a dorso-ventral ridge with both sides of the ridge convex, but some speci- 

 mens are produced to a point and the front is concave in all directions from the point. 

 The writer attempted to describe the most ventricose form, the one with the most 

 pointed ends, as a new species, but the descriptions all led back to C. ohioense. 



Occurrence — Abundant in the Mineola of Montgomery and Ralls Counties. Two 

 specimens have been collected from the Callaway of Moniteau County. 



Superfamily Trigoniacea 



Family Trigoniidae 



Genus Schizodus King 



Schizodus chemungensis (Conrad) 

 Plate 27, figures 4-7 



1842. Nuculites Chemungensis Conrad, Jour. Acad. Nat. Sci., Phila., VIII, p. 247, 



pi. 13, fig. 13. 

 1885. Schizodus Chemungensis Hall, Pal. N. Y., V, pt. 1, Lamellibranchiata sec. 2, pp. 



453-454, pi. 75, figs. 37-40, 41, 45. 

 1891. Schizodus Chemungensis Whiteaves, Cont. to Canadian Pal., p. 241, pi. 30, 



figs. 5, 5a. 

 1909. Schizodus chemungensis Grabau and Shimer, North American Index Fossils, I, 



p. 482, fig. 642b. 

 1913. Schizodus chemungensis Clarke and Swartz, Maryland Geol. Survey, Middle 



and Upper Devonian, pp. 644-645, pi. 64, figs. 3-5. 



Hall's description — "Shell large, rhomboid-ovate; length one-fourth greater than 



the height. Anterior margin broadly rounded, curving into the basal margin, which is 



sometimes nearly straight posteriorly. Post-inferior extremity angular. Posterior 



margin obliquely truncate. Cardinal line straight, less than half the length of the shell. 



