REPORT OF THE STATE PALEONTOLOGIST 1902 1103 



the posterior edge noticeably incurved. The surface is moder- 

 ately convex, and along the sides and front is a threadlike 

 border. The length of the shield, without the genal angles, is 

 30 mm, with them 37 mm; the breadth at the base 38 mm. The 

 compound eyes are prominent and project beyond the outline 

 of the shield. They are subelliptic, with a distinct angulation 

 on the inner side of each, produced by an indentation of the 

 inner anterior part. They are 14.5 mm long and 6 mm wide. 

 The facets can be made out with a good magnifying glass. The 

 eyes are located a distance equal to their own length from 

 the front of the shield and 27 mm from each other. A line 

 connecting their bases cuts the axial line a little back of the 

 center of the shield. The ocelli are on a small tumescence 

 just back of this. The ornamentation is almost obliterated, 

 but can be made out at one point, where it consists of minute, 

 short, flat, lobelike scales. 



Out of the eight species of Pterygotus that have been de- 

 scribed from American strata, and all from the Bertie water- 

 lime,- the cephalothorax of but one has been identified, that 

 of P. macrophthalmus Hall (10) . Pohlman (14) described 

 and figured one, but did not refer it to any species. It seems 

 probable that it is of an older individual of P. macroph- 

 thalmus. 



The cephalothorax of this new species differs from that of 

 P. macrophthalmus in that its length is nearly equal to 

 its breadth; the compound eyes are over one third the length 

 of the shield, elongated, angulated on the inner side, situated 

 farther back, and separated by nearly twice their length. In 

 P. macrophthalmus (15) the length of the shield is three 

 fourths the breadth; the eyes are about one third the length 

 of the shield, anterior, globular and separated by a distance 

 about equal to their length. 



In form the eyes of this species suggest those of the erettop- 

 terid species (subgenus Erettopterus Huxley), P. b i 1 o b u s 

 Salt, and P. b a n k s i i Salt, and also those of H. s o c i a 1 i s . 



