564 GEOLOGY OF OHIO. 



genus. The anterior extremity of this shell is not perfect, but, even if it 

 were, there is no doubt that the beak would have a more anterior posi- 

 tion, and the anterior margin would bend more abruptly into the lower 

 margin than is the case with T. mactriformis, H all ; moreover, the shell is 

 relatively less long. The resemblances to the published figure are also 

 striking, but since Hall does not redescribe it in volume 2 of the Paleon- 

 tology of New York, it is probable that the form he described was in 

 reality not to be considered very distinct from some other species of 

 Tellinomya, such as T. lata, Hall, for example, in which case the Penn- 

 sylvania specimen probably belongs to a different type of this genus. 

 The valve is 10 mm. long, and 8.2 mm. high. The basal margin is gently 

 rounded, increasing in convexity posteriorly as far as the upper side of 

 the umbonal ridge, whence the posterior margin takes a straight course at 

 first, becoming convex again as it meets the posterior hinge line. The 

 latter is at least 5 mm. long. At the anterior extremity of the shell the 

 basal margin curves quite suddenly upwards, following a straightish 

 course at first, becoming slightly convex as it joins the short anterior 

 hinge line. The shell is moderately convex in general, more so along the 

 umbonal ridge. The area above the latter is rather flattened, and a slight 

 tendency in the same direction is shown by a narrower area along the 

 anterior margin. The surface is covered by fine, regular concentric 

 striae, about seven to the millimeter near the posterior end of the shell. 

 There are also several more distinct and rather distant lines of growth; 

 these are grooves caused by the growth of the shell in thickness without 

 adding much to its margins. 



Nucidites (Cleidophorus) femigineum, sp. nov. 



(Plate 37, Figs. 2 a. b. 



In the same piece of rock with the type specimen of Cypricardites 

 ferrugineum, Hall and Whitfield, in the collections of the Ohio State 

 University, is a cast of a valve bearing the oblique impression character- 

 istic of many species referred to Cleidophorus. A close comparison 

 however of this impression with that of published figures of Nuculites 

 oblongatus, the types of the genus Nuculites, does not show the slightest 

 difference. It is evident that this impression in the cast corresponds to 

 a raised ridge in the shell, defining sharply the anterior muscular im- 

 pression from the general body of the shell interior. But in the shell 

 here described the lower border of this muscular impression, and the 

 posterior muscular area remain undefined. The general form is trans- 

 versely elliptical, with strongly convex extremities. The length of the 

 cast is 7.7 mm., the height 5 mm. The convexity is moderate. A groove 

 runs along the hinge line of the cast posterior to the beak and another 

 for a short distance anterior to the beak. No transverse teeth were seen. 



