208 Systematic Paleontology — Middle Devoxiax 



Coelospira acutipHcata Clarke, 1903, N. Y. State Mus., Bull. 65, p. 214. 

 Anoplotheca acutiplicata Kindle, 1912, Bull. U. S. Geol. Surv., No. 508, p. 84, 

 pi. vi, figs. 1-15. 



Description. — The shell is plano-convex, compressed and of moderate 

 size. The ventral valve is moderately convex, with the beak slightly 

 incurved.' The dorsal valve is depressed-convex, sometimes flat or con- 

 cave from compression. Surface marked by from six to eight strongly 

 angular plications; on the ventral valve two plications are slightly ele- 

 vated, giving an abrupt sinuosity in front, Avhile the central one on the 

 dorsal valve is depressed and margined on each side by a larger one. The 

 shell is concentrically marked by strong imbricating lines of growth. 



This species has previously been considered as confined to the Onondaga 

 (Corniferous) limestone; with the exception that it is doubtfully identi- 

 fied by Dr. Weller from the Monroe shales at Greenwood Lake, New 

 Jersey, which he apparently considered as of Hamilton age.^ There is 

 apparently no doubt regarding the correctness of the identification of the 

 Maryland specimens for they were submitted to Dr. J. M. Clarke who 

 identified them as belonging to this species, a conclusion fully corrobo- 

 rated by subsequent study. The Maryland specimens are principally 

 impressions preserved in bituminous shales which are considerably more 

 flattened than the specimens from the Onondaga limestone. Gutta- 

 percha impressions of some of these specimens, however, reproduce very 

 nearly the form and markings of the dorsal and ventral valves of this 

 species as shown by figures 34 and 35 of plate Ivii, vol. iv, Palaeontology 

 of New York. The plications have almost identically the same form and 

 strength as those of the figures just mentioned, are nine or ten in number 

 and rather broad and sharply marked by the imbricating concentric lines. 



' In Professor Hall's description the terms dorsal and ventral are applied to 

 the opposite valves as compared with this description as may readily be seen 

 by referring to the description on p. 3G5, vol. iv, Palaeontology, N. Y., and 

 especially by consulting figures 34 and 35 of plate 57 which are called respec- 

 tively dorsal and ventral valves. Hall and Clarke, however, reversed the nam- 

 ing of these valves in pt. ii, vol. viii, Palaeontology, N. Y., where on plate 53, 

 fig. 35 ventral valve of vol. iv reappears as fig. 32 which is called dorsal and 

 fig. 34 dorsal of vol. iv as ventral valve of fig. 34 of vol. viii. 



= Geol. Surv. N. J., Rep. on Paleontology, vol. iii, 1903, pp. 106, 107, 383. 



