added to the longer known species of eurypterids (E. remipes and E. lacustris) the following new types, all from the rocks of New York:
| Eurypterus microphthalmus | E. pachychirus |
| E. lacustris var. robustus | E. pustulosus |
| E. dekayi |
He erected the new subgenus Dolichopterus (now given full generic standing), for the species D. macrochirus and also recorded the presence of the genus Pterygotus (theretofore known only from Scotland) in the Salina waterlime, describing three species, viz, P. cobbi, P. macrophthalmus and P. osborni.
It is obvious that Hall, with his accustomed thoroughness, had availed himself of all New York collections extant, from the fact that for a decade and a half not a line was added to his investigations on American species, notwithstanding the intense activity in other branches of paleontology, and the further fact that Henry Woodward was meanwhile [1866-78] publishing his excellent Monograph of the British Crustacea of the Order Merostomata. During this period the large cement quarries at Buffalo were gradually producing a great number of striking specimens and these became somewhat widespread through the museums until, in later years and with keen and intelligent interest the proprietor of the quarry took measures to see that they were carefully safeguarded and donated to the Museum of the Buffalo Society of Natural Sciences. Some of the early collectors in Buffalo undertook to describe the supposed new material that at first found its way into that museum but, being trained in branches of science remote from paleontology, they succeeded only in creating for the most part a burdensome mass of synonyms. Thus Grote and Pitt [1875–78] described the following:
Eusarcus scorpionis, representing a new and important genus
E. grandis (=E. scorpionis)
Pterygotus cummingsi (not properly defined)
