Report of the State Geologist. 441 



of the Proeti, viz.; that having- the margin of the pygidium orna- 

 mented with spines. 



It is evident, however, that Barrande was disposed at this time 

 to relinquish this term, for in the historical introduction to vol- 

 ume i, the name Phaktonides appears as equivalent to Phaeton, 

 but without remark or comment.* This is a part of the work 

 which it is fair to assume was prepared after the body of the text 

 was completed. It was not until 1S59 that Barrande formally pro- 

 posed to replace the term Phaeton with Ph AETONiDES.f This author 

 also demonstrated, in 1852, that eight of Corda's proposed species 

 of Prionopeltis, including P. Priamus and P. Polydorxis, were 

 synonymous with his (Barrande's) Phaeton Archiaci. This last 

 named species, therefore, becomes the type of the genus Priono- 

 peltis, but the generic term, Phaeton, Barrande, has not the least 

 title to recognition.^; 



Angelin, in 1854 and 1878,§ had adopted the term Phaethon- 

 ides (with this spelling), quoting Barrande as the authority for 

 the name, but including under it not only species with a dentate 

 pygidium, but also those in which the pygidial margin is entire ; 

 the only species described by him being one of the latter class, 

 Asaphus Stokesi, Murchison. This author's conception of the genus 

 was in one sense essentially equivalent to that of Corda's interpre- 

 tation of Prionopeltis, since the forms included by the latter in his 

 group B (P. Ascanius, P. Astyanax) have been proved to possess 

 pygidia with entire margins, and Novak has separated them under 

 the name, Tropidocoryphe (type, Proetus Jilicostatus, Novak). 

 The fossils referred to Phaethonides, Angelin, in the volume of 

 the Palaeontology of New York already cited, agree with that 

 author's diagnosis. They all possess entire pygidial margins, 

 though the tubercles with which some are provided, become 

 spinules on the margin and give it the appearance of being 

 dentate. At the same time they are not congeneric with the 

 holopygous species included in Novak's Tropidocoryphe. It is 



* Page 42. 



t Parallele entre les depots siluriens de Boheme et de Scandinavie, p. 18. 



t We feel compelled to differ from the opinion recently expressed by the late Dr. Novak 

 in regard to this point (Dames and Kayser's Palaeontologische Abhandlungen, Neue Folge, 

 Bnd. 1, p. 11, 1890), who speaks of Prionopeltis as "insufficiently characterized," and con- 

 siders it better to retain Phaetonides. It could be wished that genera were as clearly defined 

 in these days as was this genus of Corda's, 45 years ago. 



§ Palseontologia Scandinavica, pt. I, p. 21. 



1891 56 



