BRACH10PODA. 183 



greater than half the width of the shell. Striae fasciculate, much curved upwards to- 

 wards the cardinal and lateral margins. 



"[Remarks] ****** 



In the dorsal valve the lamellae bordering the muscular areas 

 which diverge abruptly, and then becoming almost obsolete, curve so as to enclose a 

 broad oval space with a depressed line through the center * * In the ventral 

 valve the lamellae are broadly divergent and, becoming gradually obsolete, are nearly 

 lost and leave scarcely an impression in the cast. The imprint of the adductor muscles 



forms a small scar towards the upper part of the vascular area 



******* Hall 1859 



Dalmanella perelegans (Hall) 



Plate 44, figures 18-26 



Orthis perelegans Hall, 1857,10th Ann. Rept. N. Y. State Cab. Nat. Hist. p. 44, fig. 1. 

 Orthis perelegans Hall, 1859, Pal. N. Y., vol. Ill p. 171, pi. XIII, figs. 4-12, 1861. 

 Orthts perelegans Hall, 1883, Rept. State Geol. N. Y. for 1882, pi. XXXV figs. 32, 33 

 Dalmanella perelegans Hall and Clarke, 1892, Pal. N. Y., vol. VIII, pt. I, pp. 207, 224, 



pi. VC, figs. 34, 35. 

 Dalmanella perelegans Clarke, 1900, N. Y. State Mus., mem. 3, p. 57. 

 Dalmanella perelegans Weller, 1903, Pal. N. J., vol. Ill, pp. 305, 327, pi. XXXV, figs. 5-8. 

 Dalmanella perelegans Shimer, 1905, N. Y. State Mus., Bull. 80, p. 243. 

 Dalmanella pertlegans Schuchert, 1913, Md. Geol. Surv., L. Dev., p. 299, pi. LIV, figs. 



14-23. • 



Dalmanella perelegans Dunbar, 1919, Tenn. Geol. Surv., Bull. 21, pi. 2, fig. 9. 



Description — "Shell transversely oval; valves nearly equally convex. Dorsal valve 

 subventricose, more or less depressed along the middle from near the beak to the front; 

 beak small little elevated above the hinge line. Ventral valve elevated along the middle 

 from the beak towards the front and sloping laterally; beak small, pointed, incurved, 

 extending beyond that of the opposite valve. Cardinal margin generally sloping a little 

 from the beaks, and rounding imperceptibly into the lateral margins. Area narrow, 

 nearly half as long as the width of the shell. Foramen broad triangular, extending 

 nearly to the apex of the beak. Surface marked by fine irregular bifurcating longitudinal 

 striae, crossed by concentric lines of growth. 



"[Remarks] * * The ventral valve, although strongly elevated in the 

 centre towards the beak, is not subcarinate * * and this gibbosity is lost 

 before reaching the base. Along the middle of the dorsal valve there is a broad unde- 

 fined depression, which is more conspicuous in the upper part, from the beak half way 

 to the base; below which point, it becomes scarcely marked as a distinguishing character 

 of the shell * * . The striae of this species are often fasciculate; the stronger 

 ones separated by three, four, five or six smaller ones * * 



* * * * * * * —Hall, 1859 . 



Dalmanella quadrans (Hall) 



Plate 44, figures 27-31 



Orthis*quadrans Hall, 1859, Pal. N. Y., vol. Ill, p. 170, pi. XII, figs. 9-12, 1861. 

 Dalmanella quadrans Hall and Clarke, 1892, Pal. N. Y., vol. VIII, pt. I, p. 224. 



Description — Shell subquadrangular, valves unequally convex, anterior border 

 emarginate, anterior line of junction of valves sinuate. Ventral valve more convex than 

 dorsal valve, most convex in middle, with prominent mesial elevation from beak nearly, 

 or quite, to anterior margin; beak conspicuous, incurved. Cardinal area about f 

 width of shell, delthyrium comparatively large. Dorsal valve with pronounced mesial 

 depression from beak to anterior margin; beak inconspicuous, incurved. Surface orna- 

 mented with radiating, bifurcating, fasciculate costae — 4 to 5 in 1 mm. at anterior 

 border — crossed by concentric growth lines. 



