PALEONTOLOGY. 457 



Echinocaris sublevis. 



Plate VIII, figs. 12-14. 



Echinocaris sublevis Whitfield, Am. Jour. Sci. and Arts, 3d series, vol. 19, p. 36, 1880. 



Carapace obliquely subovate in general outline, the height equal to two-thirds 

 the length, widest and deepest behind the middle, the posterior portion projecting 

 obliquely backwards and downwards beyond the extremity of the hinge-line ■ 

 dorsal-line straight, forming a hinge-line two-thirds the length of the valve ; outer 

 margin of the valves, except on the dorsum, bordered by a narrow, slightly raised 

 and thickened rim ; anterior border nearly vertical from the extremity of the dor- 

 sal line, for about one-half the width of the valve, except a very slight rounding 

 backward to the hinge-line above ; below it slopes abruptly backward to and along 

 the basal line, and again more abruptly curving around the posterior end of the 

 valve and forward to the extremity of the cardinal line ; below which it is distinctly 

 txcavated. The portion of the valve which projects beyond the hinge is nearly or 

 quite equal to one-third the length of the valve. Surface of the valves convex, and 

 marked by ridges and tubercles. The principal ridge commences at about the an- 

 terior third of the valve, and just above the middle, as an elevated, rounded, and 

 nearly vertical ridge ; but soon bends somewhat abruptly, and is directed backward 

 in a broad, sweeping curve, at less than one-third of the height of the valve from 

 the lower margin, and gradually decreasing in strength terminates a little within 

 the margin opposite the longest part of the valve. A second and slightly stronger 

 ridgi rises irom just behind the middle of the length of the hinge, and descends 

 with a gentle forward curvature, terminates near the upper anterior end of the first 

 one. The anterior or principal tubercle is large and distinct, and situated near the 

 antero- dorsal angle of the valve, occupying the greater part of the space between 

 the front margin and the two ridges just described. Between this and the second 

 ridge the surface is elevated, forming a low tubercle. The surface of the anterior 

 tubercle is occupied by several small but distinct pustules, and the entire surface of 

 the valve covered by a minutely granulose structure. 



Abdomen apparently consisting of four free segments ; the first one being 

 short and much thicker than the others on the anterior end, but rapidly narrowed 

 posteriorly; the posterior margin being armed with several small spine-like tuber- 

 cles. The other three segments are shorter than wide, gradually decreasing in 

 strength and increasing in length backwards, the first of the three being appar- 

 ently less than half as long as wide, their posterior margins all spine bearing; a 

 long curved lateral spine on each side, with three short ones between, and all in- 

 creasing in length backwards from the first or anterior segment. 



Telson proportionally large, of a general triangular form, but slightly pro- 

 truding at the origin of the movable spines, and projecting behind into a long, 

 slender, and apparently C3-lindrical spine, making the telson with its spine about as 

 long as the four free segments together. Lateral spines cylindrical, very gently 

 curved, and standing at an angle of about forty-five degrees to the central spine 

 Surface of the telson highly convex and somewhat angular at the origin of the 

 spine. Surface of the crust of the abdomen smooth. 



This species is closely allied in the form of the carapace to E. punc- 

 tata Hall (16th Rep. State Cab. N. Y., p. 74, plate 8, %. 1); but differs 

 in the form of the nodes and ridges, and in the surface structure, also in 

 wanting the projection at the posterior end of the hinge; if this feature 

 is natural on that specimen. It is probable that the abdomen and telson 

 figured on the same plate under the name Ceratwcaris armata, belong to 

 the same species as the carapace of E. punctata, as suggested by Prof. 



