458 GEOLOGY OF OHIO. 



Hall in the explanation of plate 23, section Crustacea, Illust. Dev. Fos- 

 sils, and if so, the distinction between these parts of the two species is 

 much more marked than between the carapaces. 



Formation and Locally. — In small calcareous concretions in the 

 Erie shales (Portage and .Chemung) at Leroy, Lake county, Ohio. 



Echinocaris pustulosa. 

 Pi,ate VIII, fig. 15. 

 Echinocaris pustulosa Whitefield, Am. Jour. Sci. and Arts, 3d series, vol. 19, p. 38, 

 1880.' 



Carapace ovate, widest anterior to the middle, the greatest height equal to 

 three-fourths of the length, hinge-line straight, rather more than half as long as 

 the valve, while nearly one-third the length of the valve projects behind its ex- 

 tremity. Margin of the valve bordered by a narrow, thickened rim. Anterior end 

 of the valve slightly excavated below the hinge extremity, and the margin broadly 

 rounded in front; posterior end more pointed, while the basal line is broadly and 

 evenly curved. At the posterior end of the hinge the margin is also slightly con- 

 stricted as in front. Surface of the valve convex and marked by the characteristic 

 •nodes or ridges. The principal ridge commences in an oval node, which is situated 

 just within the anterior third of the length of the valve ; is placed vertically, just 

 above the middle of the height; and the horizontal position, which is sharply 

 elevated and slightly curved, is situated almost in the middle of the width, and 

 terminates a little less than one-fourth of the length from the posterior extremity. 

 The second ridge commences at the hinge-line near the middle of its length, and 

 descends with a slightly forward direction to within a very short distance of the top 

 of the vertical portion of the principal ridge. The anterior ridge, corresponding 

 to the anterior node or tubercle of E. sub/eviSj is narrow and vertical; of a slightly 

 sigmoid form, aud originates near the anterior extremity of the hinge-line; the 

 lower end reaching more than one-third the depth of the valve. The surface of the 

 ridges and of the valve in the postero-dprsal field, as also of the space be' ow the 

 principal horizontal ridge, is marked by correspondingly large and distinct pustules. 

 Abdomen and telson unknown. 



This species differs from C. sublevis in its slightly broader form, and 

 in the want of the obliquity of the axis of the valve with the hinge; in 

 the narrower posterior extremity, the pustulose surface, and in the form 

 of the surface ridges; most notably in the anterior one being ridge-like 

 and vertically sigmoid instead of round. The individual used in descrip- 

 tion is half an inch in length and three-eighths of an inch in its greatest 

 height. 



Formation and Locality. — In calcareous concretions in the Erie 

 shales, at Leroy, Lake county, Ohio. 



Echinocaris multinodosa. 



Plate VIII, fig. 16. 

 Echinocaris multinodosa Whitefield, Am. Jour. Sci. and Arts, 3d series, vol, 19, p. 

 38, 1880. 



Carapace elongate-subovate, about twice as long as high, rounded in front and 

 somewhat pointed behind; the basal-line straightened along'the middle portion and 

 parallel to the hinge-line; cardinal line straight and nearly half as long as the 



