CONTRIBUTIONS TO PALiEONTOLOGY. 73 



of the body has been nearly cylindrical, very gradually tapering, 

 and the crust is finely granulose. 



The three last joints, to the base of the tail-spines, measure 

 nearly an inch and three-fourths. The tail-spines are imperfect at 

 their extremities, one of the latera;! ones preserving an inch and 

 a quarter of its length. The lateral diameter of the third joint, 

 in' its crushed and flattened condition, is less than half an inch, 

 with a vertical diameter of a quarter of an inch. 



In a smaller specimen of the caudal joint and appendages, the 

 lateral spines are a little more than an inqh and a half in length, 

 the central one being a littJe shorter. 



Fig. 1. The lower side of the abdomen and caudal spines. 



Fig. 2. The upper or dorsal side, showing the short spines on the posterior edge of the artiqula- 

 tion. ' ■ 



Fig. 3. The tail-joint and appendages of another individual. 



The specimen first noticed is the first one observed in which the entire 

 characters of the body-joints could be ascertained. The fragmentary speci- 

 mens heretofore seen have been so completely flattened as to show no form 

 of the articulating faces, or the defences of the joint which are so beauti- 

 fully preserved in this one. The specimens heretofore observed in our rocks 

 have furnished no means of ascertaining the entire character of the tail- 

 spines, or their mode of attachment. In this example, the central one appears 

 to be a prolongation of the last joint of the body, while the lateral ones are 

 articulated appendages. 



This species has been found in the shales of the Hamilton group in 

 Ontario county. In the collections made by Dr. C. A. White and Mr. 

 R.P.Whitfield. 



CERATIOCARIS LONGICAUDUS (n.s.). 



PLATE I. FIGS. 4-7. 



The fragment of the abdomen is extremely flattened ; the joints 

 longer than ^vide, and proportionally longer than those of the 

 preceding species. The caudal spines are imperfect, but appear 

 to have been obtusely triangular in their original condition. 



Detached spines of similar character are found in considerable 

 numbers, varying from two to three inches in length, and some of 

 them have been longer. 



Fig. 4. A fragment showing the posterior joints of the abdomen and tail-spines. 

 Figs. 5, 6 & 7. Detached spines found in association with the preceding, and apparently belong- 

 ing to the sunJe sppcies. 



These remains occur in the black and thinly laminated upper part of the 

 Genesee slate, in the south part of Ontario county. The specimen figured is 

 the only part of the body yet observed. From the collections made by Mr. 

 E. P. Whitfield. ' 



[Senate, No. 115.] 19 



