60 NEW YORK STAT© MUSEUM 



2 Subgenus gerasaphes" Clarke 



Gerasaphes ulrichana Clarke. Geol. Minn, Pal. 1897. v. 3, pt 2, 



p. 710 



In the reddish gray compact limestone a small pygidium of an 

 asaphid was found, which possesses the broad and short form, 

 broad, flat border, strong angulation of the axis and distinct pleu- 

 ral ribs with deep pleural grooves of the pygidium, referred by 

 D'r Clarke, on account of its presenting characters of the earlier 

 representatives of the Asaphus stock at the time of the de- 

 cline of the race, together with the presence, in other parts, of 

 strong corresponding gerontic characters, to a new genus, Ger- 

 asaphes, and described as the type species, G. ulrichana. 

 Miller has claimed (in his 2d appendix to American geology and 

 paleontology 1897, p. 788) that the same form was described before 

 by Meek as Proetus spurlocki 1 ; and at the same time it 

 has been suggested that these fossils may represent the young of 

 A s a p h u s m e g i s t u s , to which Proetus spurlocki 

 was referred by Miller in the first edition of his American geology 

 and paleontology. It does not seem, with the evidence thus far 

 gathered, opportune to unite these species and the subgenus 

 Gerasaphes with the common Trentoin Isotelus, for it must 

 be assumed that Hall as well as Meek and Clarke described 

 their species with the knowledge of the characteristics of 

 the young of Isotelus. Hall and Meek figure specimenis- of 

 Isotelus side by side with this new form; Meek, even a young 

 Isotelus on the same plate with his Proetus spurlocki, 

 and Clarke compares his form with the immature stages of the 

 race. On the other hand, it might be urged that all these forms 

 described as new refer to very small specimens, and have been 

 found at different horizons, Proetus spurlocki in the 

 lower part of the Cincinnati group, G. ulrichana in the 

 Utica beds, thus giving a form which should represent only a 

 final stage of development a rather long range, and also that all 

 have been found associated with Isotelus gigas-maxi- 

 mus (= me gist us); facts which would suggest the specific 



i Am. jour. sci. 1872. 3:426. 



