The 20th century would see the description of additional species of Pterygotus in North America as well, including the Silurian P. marylandicus (1964, Maryland, USA) and P. monroensis (1902, New York, USA), the Early Devonian P. carmani (1961, USA) and P. floridanus (1950, Florida, USA) and the Middle Devonian P. gaspesiensis (1953, Quebec, Canada).

Fossil remains of pterygotid eurypterids, bearing the distinct scale-like ornamentation known from the group, had been reported from eastern Canada as early as 1846, when researcher William Edmond Logan reported the occurrence of an animal "bearing strong resemblance to Murchison's Pterygotus problematicus" in Silurian-Devonian deposits of Gaspé, Quebec.
The fossils, eventually identified as being exclusively of Devonian age, were first tentatively referred to P. atlanticus (now synonymized with P. anglicus), which had been discovered in relatively close proximity to the Gaspé fossils, on the account of the P. atlanticus material being so fragmentary that it was impossible to tell whether or not they represented the same species.
They were described by Loris S. Russell as belonging to the new species P. gaspesiensis in 1953.

John William Dawson in 1861 named a new species of lycopod plant, Selaginites formosus, based on alleged remains of stems and branches found at Gaspé.
Salter convinced Dawson that fossils of S. formosus actually were fragmentary remains of a eurypterid, as confirmed by further findings.
Dawson reclassified it as a eurypterid in 1871.
Kjellesvig-Waering in 1964 assigned it as a questionable species of Pterygotus.

In 1921, Ruedemann described an eurypterid fauna from the Vernon Formation of Pittsford, New York.
Among them, the species P. vernonensis was erected based on two small short carapaces.
The outline and position of the eyes suggest an assignation to the genus Pterygotus, differing from P. monroensis in being nearly rectangular in shape and with a straight transverse frontal margin.
He suggested a relationship with Slimonia, but he did not assigned it due to the lack of more material indicative of the latter.
Although it was later placed on the genus Waeringopterus, Samuel J. Ciurca Jr. and O. Erik Tetlie concluded in 2007 that the holotype does not really have eyes and is nothing more than an incomplete body segment.
Therefore, they regarded the species as a nomen dubium (a dubious species).

P. floridanus, recovered from deposits of Lochkovian age in Florida, extended the known range of eurypterids on the continent over 800 km (500 miles) south.
Prior to its discovery, eurypterids in North America were only known from the northern parts of the continent, with New York State representing the most fossil-rich state.
The remains of P. floridanus were first uncovered by G. Arthur Cooper in Suwannee County, Florida, and the fossils consist of a fixed ramus of the chelicera as well as fragments of the abdominal plates and tergites and were concluded to represent a new species of Pterygotus by Erik N. Kjellesvig-Waering in 1950.
It most closely resembles P. cobbi and P. barrandei, differing from P. cobbi in its more developed central tooth and the arrangement of the smaller teeth of the claws and from P. barrandei in that P. floridanus has a more slender ramus.

P. carmani is the most commonly found eurypterid in the Lower Devonian deposits of Lucas County, Ohio.
Described by Erik N. Kjellesvig-Waering in 1961 and named in honor of Dr. J. Ernest Carman of the Ohio State University, the first to discover eurypterids at the locality where the P. carmani remains were found, P. carmani is primarily known from incomplete chelicerae and gnathobases of coxae.
Alongside the two coxae and three chelicerae part of its original description, known fossil remains also include a metastoma and a pretelson.
All of these original fossil specimens were designated by Kjellesvig-Waering as paratype specimens upon the original description of the species.
The designated type specimen is an incomplete chelicerae, PE5105, that remains housed at the Chicago Natural History Museum
The 20th century would see the description of additional species of Pterygotus in North America as well, including the Silurian P. marylandicus (1964, Maryland, USA) and P. monroensis (1902, New York, USA), the Early Devonian P. carmani (1961, USA) and P. floridanus (1950, Florida, USA) and the Middle Devonian P. gaspesiensis (1953, Quebec, Canada).
Fossil remains of pterygotid eurypterids, bearing the distinct scale-like ornamentation known from the group, had been reported from eastern Canada as early as 1846, when researcher William Edmond Logan reported the occurrence of an animal "bearing strong resemblance to Murchison's Pterygotus problematicus" in Silurian-Devonian deposits of Gaspé, Quebec. The fossils, eventually identified as being exclusively of Devonian age, were first tentatively referred to P. atlanticus (now synonymized with P. anglicus), which had been discovered in relatively close proximity to the Gaspé fossils, on the account of the P. atlanticus material being so fragmentary that it was impossible to tell whether or not they represented the same species. They were described by Loris S. Russell as belonging to the new species P. gaspesiensis in 1953.
John William Dawson in 1861 named a new species of lycopod plant, Selaginites formosus, based on alleged remains of stems and branches found at Gaspé. Salter convinced Dawson that fossils of S. formosus actually were fragmentary remains of a eurypterid, as confirmed by further findings. Dawson reclassified it as a eurypterid in 1871. Kjellesvig-Waering in 1964 assigned it as a questionable species of Pterygotus.
In 1921, Ruedemann described an eurypterid fauna from the Vernon Formation of Pittsford, New York. Among them, the species P. vernonensis was erected based on two small short carapaces. The outline and position of the eyes suggest an assignation to the genus Pterygotus, differing from P. monroensis in being nearly rectangular in shape and with a straight transverse frontal margin. He suggested a relationship with Slimonia, but he did not assigned it due to the lack of more material indicative of the latter. Although it was later placed on the genus Waeringopterus, Samuel J. Ciurca Jr. and O. Erik Tetlie concluded in 2007 that the holotype does not really have eyes and is nothing more than an incomplete body segment. Therefore, they regarded the species as a nomen dubium (a dubious species).
P. floridanus, recovered from deposits of Lochkovian age in Florida, extended the known range of eurypterids on the continent over 800 km (500 miles) south. Prior to its discovery, eurypterids in North America were only known from the northern parts of the continent, with New York State representing the most fossil-rich state. The remains of P. floridanus were first uncovered by G. Arthur Cooper in Suwannee County, Florida, and the fossils consist of a fixed ramus of the chelicera as well as fragments of the abdominal plates and tergites and were concluded to represent a new species of Pterygotus by Erik N. Kjellesvig-Waering in 1950. It most closely resembles P. cobbi and P. barrandei, differing from P. cobbi in its more developed central tooth and the arrangement of the smaller teeth of the claws and from P. barrandei in that P. floridanus has a more slender ramus.
P. carmani is the most commonly found eurypterid in the Lower Devonian deposits of Lucas County, Ohio. Described by Erik N. Kjellesvig-Waering in 1961 and named in honor of Dr. J. Ernest Carman of the Ohio State University, the first to discover eurypterids at the locality where the P. carmani remains were found, P. carmani is primarily known from incomplete chelicerae and gnathobases of coxae. Alongside the two coxae and three chelicerae part of its original description, known fossil remains also include a metastoma and a pretelson. All of these original fossil specimens were designated by Kjellesvig-Waering as paratype specimens upon the original description of the species. The designated type specimen is an incomplete chelicerae, PE5105, that remains housed at the Chicago Natural History Museum 
Pterygotus