Contribution fi to Invertebrate Palaeontology. 567 



the distinction between tliese parts of the two species is much more 

 marked than between the carapaces. 



Formation and Locality. — In small calcareous concretions in the 

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



Ecliiiiocaris piistiilosa. 



Plate XII, fig. 1.5. 



Echinocuris pustulosa Whitfield, Am. Jour. Sci. and Arts, 3d scries, vol. 19, 

 p. 38, 1880, 



Carapace ovate, widest anterior to tlie 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 extremity. Margin of the valve Ijordered 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, wliile the 

 basal line is broadly and evenly curved. At the posterior end of the hinge 

 the margin is also slightly constricted as in front. Surface of the valve convex 

 and marked by the characteristic nodes or ridges. The principal ridge com- 

 mences 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 sharjjly 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 com- 

 mences 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. suhlevis, is narrow and nearly vertical ; of a 

 slightly sigmoid form, and 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-dorsal field, as also 

 of the space below the principal horizontal ridge, is marked by correspond- 

 ingly 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 description 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 Co., Ohio. 



