BRACHIOPODA. 249 



Family Meristellidae 

 Genus Nucleospira Hall 



Nucleospira cf. ventricosa (Hall) 

 Plate 66, figures 1-3 



1857. Spirifer ventricosa Hall, Tenth Ann. Rept. N. Y. State Cab. Nat. Hist., p. 57. 

 1859. Nucleospira ventricosa Hall, Nat. Hist. N. Y. Pal., vol. 3, p. 220, pi. 14, fig. 1; 



pi. 28b, figs. 2-9, 14, 1861. 

 1913. Nucleospira ventricosa Schuchert, Geol. Surv., Md. Low. Dev., p. 430, pi. 73, 

 figs. 10-12. 



Description— Shell small, transversely oval in outline. The dimensions of an im- 

 perfect brachial valve are: Length approximately 9 mm., width 11 mm. A smaller 

 brachial valve measures 6 mm. in length and 8 mm. in width. The cardinal margins 

 slope abruptly from the beaks, and terminate in well rounded extremities. 



Brachial valve convex, median portion most elevated, and marked with a shallow 

 sinus extending from the beak to the anterior margin. Beak pointed, moderately ele- 

 vated. Surface marked by indistinct concentric growth lines. 



Concerning the pedicle valve Hall says: "Ventral valve having a narrow sinus 

 extending down the centre from beak to base; beak projecting above the other, strongly 

 incurved and pointed (in many specimens the beaks are nearly equal)"— Hall, 1859. 



Remarks — Three or four fragmentary brachial valves have been observed in the 

 collection, which resemble Nucleospira ventricosa Hall, from the New Scotland beds of 

 New York, and they are undoubtedly a later expression of that species. Except that 

 the specimens observed possess more steeply sloping cardinal margins there seems 

 to be no important variation from this New Scotland species. 



Horizon— Lower beds. 



Figured specimens No. 27494, Walker Museum. 



Genus Meristella Hall 



Meristella ampla sp. no v. 



Plate 66, figures 9-11 



Description — Shell from medium size to large, sub-quadrate in outline, relative 

 length and width variable, but generally the width slightly greater than the length. 

 The dimensions of the holotype, which is an average sized brachial valve are: length 

 36 mm., width 37 mm. Cardinal margins slope steeply to the beaks, extremities rounded. 



Pedicle valve moderately convex, the greatest convexity in the umbonal region, 

 apparently flattened anteriorly. Beak broad and flat, incurved slightly. A cast of the 

 interior shows a large, strongly defined muscular area which is longitudinally striate. 

 A long narrow process projects from the muscular platform to the beak. The region 

 surrounding the muscular area is rugose. 



Brachial valve more convex than the opposite, maximum convexity in the umbonal 

 region, and a flattening occurs anteriorly similar to that of the opposite valve. Beak 

 incurved slightly. 



Surface of both valves essentially smooth with faint lines of growth. 



Remarks — This form is represented by the separate valves only. It resembles 

 Meristella sub-quadrata Hall, but has a less distinctly quadrate outline, the pedicle 

 valve is less convex, and the anterior margin more broadly rounded. It differs from 

 associated species in the larger size of the full-grown examples, and in the greater 

 tendency to quadrate outline. 



Horizon — Lower beds. 



Holotype and Paratypes No. 27487, Walker Museum. 



