124 PALEONTOLOGY OF ILLINOIS. 



sulcus, bounded by prominent salient angles without denticles 

 and divided in the centre by a Ioav but distinct continuous 

 carina; anterior margin rounded and set along the median line 

 with a row of round flattened tubercles about a line in diame- 

 ter, and separated by intervals of equal or slightly greater 

 breadth. On either side of this larger row of tubercles is a 

 second of about half their size below, of nearly equal size above, 

 behind these are, on either side, 20 to 25 longitudinal parallel 

 rows of similar, but smaller, tubercles, which progressively 

 diminish in size to the posterior or convex border, and are very 

 uniformly distributed over all of the lateral surfaces. These 

 tubercles are accurately arranged in longitudinal rows, most of 

 which are continuous from base to summit. They also exhibit 

 an imperfect transverse alignment. Those of the anterior me- 

 dian line are flattened and smooth, as though somewhat worn, 

 but the others generally, and these partially, are beautifully 

 ornamented by numerous, sharp, converging carinas, which rise 

 from the base, and, when not obliterated, cover the entire sur- 

 face. They are stringent on the upper side of the tubercles, 

 the interval between the tubercles seems to have been smooth 

 bone without enamel, the tubercles having the appearance of 

 globules of brilliant black glass, and look as though they had 

 exuded through pores in the bone, and had congealed on the 

 surface, studding it with gems. Under the lens these orna- 

 mented globules are exceedingly pretty, and have suggested 

 the specific now given. On some of them the raised lines 

 have a spiral arrangement giving them the appearance of seeds 

 of the Cliara. 



That part of the spine which was enveloped in the integuments partakes of 

 the general curve of the exposed portion, its sides are flattened and smooth, 

 and converge to form a sub-acute edge in front, on which is a tubercular exeres- 

 sence as large as half a pea, just below the first of the enameled tubercles. 

 The posterior border of the basal portion is deeply sulcated to its extreme 

 point by the continuation of the pulp cavity, which was apparently open pos- 

 teriorly from the point where the ornamentation ceases. The margins of this 



