PLATE 60. 



Fig. 1. 291. 1. OoYGiA? VETUSTA. (Pag. 227.) 



Fig. 2, 292. 3. Asaphus? extans. (Pag. 228.) 



2 o. A caudal shield. 2 b. Lateral view of the same. 



2 c. Another fragment, showing nine articulations of the thorax. 



Fig. 3. 293. 1. Caltmene multicosta. (Pag. 228.) 



Fig. 4. 40. 2. ILL.ENUS ceassicauda. ( Pag. 229.) 



4 a. The caudal shield of a large individual. 



4 6. Middle lobe of the cephalic shield, the lateral portions being separated at the sutures. 



4 c. Lateral view of a small entire specimen. 



4 d. Dorsal view, showing the great width of the middle lobe, and abrupt incurving of the cephalic shield. 



Fig. 5. 294. 3. iLLiENirs trentonensis. (Pag. 230.) 



Fig. 6. 295. 4. Ill.s:nus latidorsata. (Pag- 230.) 



6 a. The fragment, natural size. t> b. Three of the articulations enlarged, showing the lamellose stris. 



Fig. 7. 43. 1. IsoTELus oioAS. (Pag. 231.) 



7 a. A specimen preserving the thorax, caudal extremity, and central lobe of the buckler. (The base of the 



latter is too far extended in the engraving.) The caudal shield is denuded of the shell. 

 7 b, e. The maxillary portions or cheeks of the buckler. e, e. The eyes. 



7 d. Inside of the lower crust of the cephalic shield, the upper part having been separated at the lateral suture. 

 7 e,f. Lower side of the cephalic shield, towards the extremities of which the upper and lower crusts are 



folded together, so as to present the appearance of projecting spines. 

 7 g. The epistoma or labrum, the place of which is indicated in the centre of the lower side of the previous 



figure. Two circular depressed spots are represented, which are always observed in well preserved 



specimens : these probably indicate the points for the attachment of muscles or tendons upon the inside. 

 7 h. Central lobe of the cephalic shield. 7 i. Same part of a larger individual. 



