BUFFALO SOCIETY OF NATURAL SCIENCES 219 



se, but not for any phyletic reasons, as derivatives from Appalachia, 

 the Pittsford constituting the upper part of the Shawangunk (see p. 

 1 01 above). The problematic form from the Portage sandstone re- 

 ferred to S.? wrightianus is too incomplete to be of much value. It 

 probably belongs to Stylonurus; it certainly occurs in an otherwise 

 unfossiliferous deposit which has been interpreted by Grabau as 

 partly of river floodplain and partly of wind-blown perhaps loess-like 

 origin (87, 553, 569). Finally, the Upper Devonic yields two species 

 of Stylonurus: one, 5. beecheri described from a single individual, 

 none too complete, from the Chemung sandstones of Warren, Penn- 

 sylvania ; the other S. (Ctenopterus) excelsior from two specimens from 

 the Catskill beds of New York and Pennsylvania. This latter species 

 is related in many respects to S. (Ctenopterus) cestrotus from the Sha- 

 wangunk, both belonging to the same sub-genus. The Catskill is a 

 continental deposit whose material as shown first by Grabau (86) and 

 later by Barrell was derived from Appalachia. The specimens of S. 

 excelsior were beyond a doubt washed out into the Chemung sea, 

 since all of the species of Stylonurus so far known from North America 

 came from Appalachia, as has just been demonstrated. 



Having now followed the history of this one genus from Ordovicic 

 through Devonic time and found that it always lived in the rivers of 

 Appalachia, let us return to the genus Dolichopterus in the Normans- 

 kill beds, and trace its subsequent occurrences. As in the case of 

 Stylonurus, the specific relations of the Normanskill form cannot be 

 determined, for only a single small carapace is known, but the point 

 of especial interest is the occurrence thus early of a Dolichopterus. 

 This genus is represented by two species certainly, and one doubt- 

 fully, in the succeeding Schenectady beds. Two specimens described 

 under the new species of D. latifrons by Clarke and Ruedemann agree 

 "closely with D. otisius" from the Shawangunk in the posterior con- 

 traction of the carapace (39, 270). The carapaces and metastomes of 

 D. frankfortensis (Schenectady) do not seem to show close relationship 

 to other species of the genus, though one metastoma "has been found 

 which recalls that of D. macrochirus" from the Bertie (39, 269). A 

 few fragments having certain Dolichopterus and certain Eurypterus 

 characteristics have been referred to E.? (Dolichopterus?) stellatus, 

 but they are of no value in the present discussion. Thus it is seen 

 that in the meagre, unsatisfactory material from the Normanskill 

 representative of Dolichopterus, one species shows affinities to a 

 Shawangunk form, and one specimen of a second species recalls char- 



