168 Description of a neiv Trilobitc. 



the front is rounded and mamraillary ; the anterior lateral margin of 

 the other lobe on each cheek is lost, but the rest is very perfect. 

 The edge nearest the abdomen runs parallel with the articulations 

 of the vertebral column, and from its inner edge the front of the 

 buckler starts up in high relief. Between the front and the articu- 

 lations of the back it is quite narrow, but it swells up and enlarges 

 as it proceeds laterally, so as to give to the whole buckler a pente- 

 lobate appearance. In the C. variolaris the external angles of the 

 buckler have a prolongation down the sides of the abdomen to the 

 sixth articulation : our mutilated fragment will not permit a com- 

 parison in this particular, as one articulation of the back is all that 

 remains. There is no appearance of eyes, though there can be but 

 little doubt that these organs will yet be discovered in other speci- 

 mens. The breadth of the buckler is one inch and a half; and the 

 length, measuring over the front, is the same. 



For this highly interesting species, I am indebted to the kindness 

 of Dr. William Blanding, whose indefatigable labors have greatly 

 contributed to illustrate several departments of American natural 

 history. In a note from that gentleman, which accompanied our fos- 

 sil, he remarks, " It was obtained from the limestone used in con- 

 structing the national road, the quarry of which is within two miles 

 of Springfield, Ohio." The limestone is of a light gray color, and 

 the fossil is spangled with little crystalline particles of that mineral. 



In Parkinson's Organic Remains, vol. iii. plate IT, figure 16, 

 there is a representation of the anterior portion of the C. variola- 

 ris, to which Professor Brongniart refers. The following sTiort ac- 

 count of it is given at p. 266, which will enable those who are cu- 

 rious, to compare our species with it. " In this animal, the lobular 

 divisions seem to have very nearly corresponded with those of the 

 Dudley species ; but the structure of the head part differs exceed- 

 ingly from every other species. In this fossil, instead of the ap- 

 pearance of the distinct parts of a face, there are three large round 

 protuberances, the middle being the largest, and all these protuber- 

 ances are closely beset with small tubercular elevations. These pro- 

 tuberances occupy nearly the whole space of the head, the eyes being 

 placed on the centre of each of the lateral elevations. The matrix of 

 this is a fine white limestone, but I am not able to say where it was 

 obtained." 



