PELECYPODA. 115 



1913. Goniophora hamiltonensis Prosser and Kindle, Maryland Geol. Survey, Middle 

 and Upper Devonian, pp. 271-272, pi. 33, figs. 11-13; Clarke and Swartz, p. 

 651, pi. 65, fig. 3. 

 Hall's description — "Shell large, trapezoidal; length more than twice the height; 

 basal margin gently curving, sometimes nearly straight and slightly affected by the 

 sinus. Posterior margin obliquely truncate. Anterior margin concave below the beak 

 and abruptly rounded below. Cardinal line very slightly arcuate, extending for two- 

 thirds the length of the shell; margins inflected, forming a long, deep escutcheon Valves 

 moderately convex below the umbonal ridge, and concave above it to the cardinal 

 line. Beaks sub-anterior, small, closely incurved, situated from one-fourth to one-sixth 

 the length of the shell from the anterior margin. Umbonal ridge angular, strongly de- 

 fined, arching over the beaks and extending in nearly a direct line to the post-basal 

 extremity. Umbonal region scarcely gibbous, separated from the anterior end by a broad 

 undefined sinus, which becomes obsolete in some specimens, owing to compression. 

 Test of moderate thickness, marked by regular, prominent, lamellose striae." 



Remarks — This is a rare form in the Snyder Creek shale and only eight specimens 

 are in the University of Missouri Collections. The specimens differ in no essential 

 details from those from other localities. A small part of the posterior end is missing 

 from each specimen. 



Occurrence — Snyder Creek shale of Callaway County. 



Order TELEODESMACEA 

 Superfamily Lucinacea 



Family Lucinidae 

 Genus Paracyclas Hall 



Paracyclas elliptica Hall 



Plate 36, figure 1. 



1843. Paracyclas elliptica Hall, Geol. N. Y., pt. IV, Rep. Fourth Dist., p. 171, t. 67, 



fig. 2. 

 1872. Lucina {Paracyclas) elliptica, var. occidentalis , Hall and Whitfield, Twenty- 

 fourth Ann. Rep. N. Y. State Mus. Nat. Hist., p. 189. 

 1883. Paracyclas elliptica Hall, Pal. N. Y. vol. V, pt. I, pi. 72, figs. 23-30. 

 1885. Paracyclas elliptica Hall, Pal. N. Y., vol. V, pt. 1, Lamellibranchiata 2, p. 440, 



pi. 72, figs. 23-33, pi. 95, fig. 18. 

 1889. Paracyclas elliptica Nettleroth, Kentucky Fossil Shells, pp. 209-210, pi. 2, figs. 



1-3. 

 1909. Paracyclas elliptica Grabau and Shimer, North American Index Fossils, 1, pp. 



554-555, fig. 760d. 

 1911. Paracyclas elliptica Cleland, Wisconsin Geol. Nat. Hist. Surv., Bull. 21, p. 117, 

 pi. 25, figs. 3-5. 

 Hall's description — "Shell large, sub-circular or broadly sub-elliptical (subject 

 to great variation in form from compression); length and height about equal. Pallial 

 margin regularly curving from the extremities of the hinge. Cardinal line short, more 

 than one-third the length of the shell, slightly arcuate. Valves regularly convex, some- 

 what regularly gibbous in the middle. Beaks a little anterior to the middle, small, 

 appressed and closely incurved, rising but little above the hinge line. Umbonal slope 

 defined above by a depression extending from the beaks to about the middle of the pos- 

 terior extremity, distinctly limiting the post-cardinal slope of the valves. Test thin, 

 Surface marked by fine concentric striae, which are aggregated into fascicles at irreg- 

 ular distances. Ligamental groove narrow and elongate. Posterior musclar impression 

 just within the post cardinal margin and below the ligamental groove. Pallial line parallel 

 with the basal margin, marked in the cast by a row of elongate nodes, which are the 



