| Original Name | Present Name or Status |
| P. acuticaudatus Pohlman | Pterygotus buffaloensis (Pohlman) |
| P. banksii Salter | P. (Erettopterus) banksii Salter |
| P. buffaloensis Pohlman | P. buffaloensis (Pohlman) |
| P. cobbi (P. cummingsi) Semper | P. cobbi Hall |
| P. comes Barrande | P. bohemicus Barrande |
| ? P. cummingsi Grote and Pitt | P. buffaloensis (Pohlman) |
| P. cummingsi Grote and Pitt | P. cobbi Hall |
| P. cyrtochela Barrande | Doubtfully identified, no standing |
| P. expectatus Barrande | Doubtfully identified, no standing |
| P. globicaudatus Pohlman | Eurypterus pustulosus Hall |
| P. globicaudatus Laurie | Eurypterus pustulosus Hall |
| P. hibernicus Baily | Eurypterus hibernicus (Baily) |
| P. macrophthalmus ? Pohlman | P. buffaloensis (Pohlman) |
| P. mediocris Barrande | Doubtfully identified, no standing |
| P. osborni Hall | Pterygotus macrophthalmus Hall |
| P. perornatus Salter | P. bilobus var. perornatus Woodw. |
| P. perornatus var. plicatissimus | P. bilobus var. perornatus Woodw. |
| P. problematicus Agassiz | P. problematicus Salter |
| P. problematicus Banks | P. gigas Salter |
| P. problematicus Strickland and Salter | P. problematicus Salter |
| P. punctatus Salter | Eusarcus punctatus (Salter) |
| P. pugio Barrande | Doubtfully identified, no standing |
| P. quadricaudatus Pohlman | Pterygotus buffaloensis (Pohlman) |
| P. raniceps (Woodw.) | Eusarcus raniceps (Woodw.) |
| P. sp. Whiteaves | P. atlanticus Clarke and Ruedemann |
| ? P. sp. Sarle | P. monroensis Sarle |
CHAPTER II
A Résumé of the Opinions on the Habitat of the Eurypterida
From 1818 when the first Eurypterus was discovered in America by Dr. S. L. Mitchell until 1900, the order of the Eurypterida was held to be made up of marine organisms. This belief in the marine habitat of the oldest Arthropoda known suddenly became the centre of contention at the beginning of the present century in spite of its long period of security. As soon as geologists considered the possibility of origins other than marine for conglomerates, shales and even limestones, there arose discussion as to the nature of the beds in which eurypterids had been found and opinions were perceived to be divergent. It is of interest, then, to take up a systematic review of the literature for the last hundred years and to note what has been the general opinion of geologists and palaeontologists about the
