NO. 2177. FOSSIL FISHES IN NATIONAL MUSEUM— EASTMAN. 241 



Family PSAMMOSTEIDAE Traquair. 



Genus PSAMMOSTEUS Agassiz. 



Syn. riocosteus and Fsammolepis Agassiz; Dyptychosteus Preobrajensky. 



This genus is represented in the United States National Museum 

 collection by a few fragmentary remains from the Devonian of north- 

 west Russia, received through the School of Mines at St. Petersburg. 

 Until about a score of years ago little was known concerning the 

 skeletal organization of the primitive chordates belonging to tliis and 

 related genera, and competent authorities assigned Psammosteus to a 

 position among the Elasmobranchs. In October, 1894, however, Dr. 

 R. H. Traquair * published a description of a new species of Psam- 

 mosteus, named by him P. taylori, from the Upper Old Red Sandstone 

 of the Elgin district, Scotland, and in the light of his subsequent dis- 

 covery of nearly complete specimens of Dre-panaspis in the Lower 

 Devonian of Germany, the Scottish author ^ suggested that Psam- 

 mosteus should be placed in close association with Drepana^'pis in the 

 Heterostracous section of the Ostracodermi. Some further details 

 concerning the body armor of P. taylori were made known by Dr. A. 

 Smith Woodward ^ in 1911, the result of which was to confirm Doctor 

 Traquair's reference of the genus to the Ostracoderms. 



About the time when Psammosteus was first discovered in Scot- 

 land, in 1895, a brief notice of the various plates and spines of the 

 same genus which are preserved m the Museum of the University of 

 Dorpat was pubhshed by Dr. A. S. Woodward/ who had examined 

 the remains three years previously, and in this article a figure was 

 given of a dorsomedian shield of P. paradoxus Agassiz, from the Upper 

 Devonian of Neuhausen, Livonia. A copy of Woodward's illustra- 

 tion of this plate is shown in the accompanying text-figure 1 ; and the 

 reason for our noticing it thus particularly is because the identical 

 specimen was again figured in 1910, by a Russian geologist who had 

 evidently overlooked the earhcr writings of Traquair and Smith 

 Woodward, and proposed to establish a new genus and species upon 

 the evidence of the plate in question. 



In this paper by Doctor Preobrajensky,^ the text of which is in 

 Russian, the question of nomenclature is still further complicated by 



> Ann. Scott. Nat. Hist., vol. 3, 1894, p. 225; also The Extinct Vertebrata of the Moray Firth Area, in 

 Brown and Buckley's Vert. Fauna Moray Basm, 1896, pp. 260-263. 



« Traquair, R. H. Report on fossil fishes . . . from the Silurian rocks of the South of Scotland. 

 Trans. Roy. Soc. Edinb., vol. 39, 1899, p. 848. 



» Woodward, A. S. On the Upper Devonian Ostracoderm, Psammosteus taylori. Ann. Mag. Nat. Hist., 

 ser. 8, vol. 8, 1911, pp. 648-652. 



< Woodward, A. S. The problem of the primaeval Sharks. Natural Sci., vol. 6, 1895, pp. 38-43, fig. 1. 



s Preobrajensky, J. A. Ueber einige Vertreter der Familie der Psammosteidae Ag. Sitzber. Natiu-forscli. 

 Gesell. Univ. Dorpat, vol. 19, 1910, pp. 21-36. pi. 2. 



flDOOS"— Proc.N.M.v<il..^.2— 17 16 



