'M PPP. UKPoirr OF I'UotiUKss. .iamks hall. 



The specimen represented in P^ig. 1 of Plate IV is here 

 given in outline with the metastonia and maxillse in posi- 

 tion. These parts can scarcely be detected on the finished 

 drawing on acconnt of the obscnrity of the specimen, and 

 the falsification which would result if these features were 

 brought out conspicuously. 



Fig. 4 EuRYPTERis Mansfieldi. 



-metastoma. 6, b. — maxillae. 



^ Foriaatioii and locality. — Found in the shale immedi- 

 ately below the Darlington cannel coal, near Cannelton, 

 Darlington township, Beaver county, Pennsylvania. Hor- 

 izon, Alleghany river series. 



EURYPTERUS STYLUS, 71. Sp. 

 Plate V, Figs. 12-15. 



Carapace broadly semi-oval or semi-circular ; length more 

 than two-thirds the width ; margin distinctly limited. Eyes 

 situated on a line across the middle of the length of the 

 carapace and distant about one-fourth the breadth from the 

 margin. 



Abdomen wide to the seventh segment, then abruptly 

 narrowed and gradually decreasing in width to the telson. 

 The first somite is anchylosed to the carapace. The widest 



