230 Systematic Paleontology — Middle Devonian 



randalU from Cumberland/ and this specimen is represented as having 

 smooth muscular impressions while fig. 25 of the same plate represents 

 an internal impression of N. lirata with striated posterior muscular im- 

 pressions. This species is readily distinguished from the associated ones 

 by the strong concentric undulations and fine radiating striae. 



Length, 15 mm.; height, 11 mm. 



Occurrence. — Homney Formation, Hamilton Member. East bank 

 Evitts Creek below Wolfe Mill. 



Collections. — Maryland Geological Survey; New York State Museum; 

 American Museum of Natural History. 



Nucula varicosa Hall 

 Plate XXV, Figs. 11-16 



Nucula varicosa Hall, 1870, Prelim. Notice Lamellibranchiata 2, p. 2. 

 Nucula varicosa Hall, 1885, Pal. N. Y., vol. v, pt. i, Lamellibranchiata ii, p. 



319, pi. xlvi, figs. 12-23; pi. xciii, fig. 4. 

 Nucula varicosa Clarke, 1903, N. Y. State Mus., Bull. 65, p. 463. 



Description. — Shell of medium size, ovate- triangular ; length somewhat 

 greater than the height; basal margin curving, more abruptly rounded 

 posteriorly ; post-cardinal margin arcuate or subtruncate ; anterior end 

 very short and abruptly rounded below. Valves gibbous, ventricose in 

 the umbonal region. Beaks subanterior, prominent, incurved, arching 

 over the hinge-line. Umbonal slope narrowly rounded, arching" upward 

 and extending from the beaks to the post-basal extremity; post-cardinal 

 slope narrow. Test strong, marked by fine, irregular, concentric striae, 

 and by numerous varices of growth, which are closely arranged on the 

 marginal portions of the shell. Hinge strong, and posterior to the beaks 

 it is marked by a narrow row of ver\' fine transverse teeth. Specimens 

 vary in length from 15-18 mm.; and in height from 12-16 mm. Hall, 

 1885, condensed. 



The varices of these specimens are not quite so strong as on the type 

 specimens of this species nor the beaks as high, yet they are higher than 



' Pal. N. Y., vol. v, pt. i, Lamellibranchiata ii, explanation figures 26 and 

 27 of plate 45. 



