| Largest carapace observed: | Centimeters | |
| Width | 11.5 | |
| Length | 8.8 | |
| Length of lateral eye | 4 | |
| Largest coxa observed: | ||
| Length of anterior edge | 20 | |
| Length of manducatory edge | 8.2 | |
| Largest metastoma: | ||
| Length | 7 | |
| Width | 4.2 | |
| Largest tergite: | ||
| Length | 10 | |
| Width about | 37[1] | |
| Largest telson: | ||
| Length | 11.5 | |
| Width | 11 | |
The size of the largest tergite and coxa suggests that this species reached truly gigantic dimensions for merostomes and rivaled the British P. anglicus which Woodward [loc. cit. p. 43] felt justified in concluding "attained a length of six feet, and a breadth of nearly two feet, at the widest part of its body." From the relative length and width of the tergites in our specimens we infer that P. buffaloensis was more slender than the British species. The largest tergite leads us to the conclusion that it belonged to an individual 1.65 m or 5 feet, 5 inches long. The very large base from the waterlime at Buffalo [pl. 79, fig. 1] must by comparison of the length of its manducatory edge with that of other specimens, have been the formidable masticating organ of an individual not less than 2 m (2.01 m) or 6 feet, 7 inches long.
The waterlime has furnished the chelae of still another gigantic eurypterid, that of P. cobbi. As the relative dimensions of the chelae to
- ↑ Obtained at Litchfield and possibly belonging to P. macrophthalmus.
