60 NEW YORK STATE MUSEUM 



2 Subgenus gerasaphes Clarke 



Gerasaphes ulrichana Clarke. Geol. Minn. Pal. 1S!>7. v. :^, pt 2, 



p. 710 



In the reddish gray compact limestone a small pygidium of an 

 aeapliid was found, which i>ossesses the broad and short form, 

 broad, Hat border, strong annulation of the axis and distinct pleu- 

 ral ribs with dc^p pleural grooves of the pygidium, referred by 

 Dr Clarke, on account of its presenting characters of the earlier 

 repressentatives of the Asaphus stcK'k at the time of the de- 

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

 strong corresi>ondiTig gerontic characters, to a new genus, Ger 

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

 Miller has claimed (in his 2d apix'ndix to American geology and 

 jHileantology 1S97, p. 788) that the eame form was described before 

 by Meek as P r o e t u s s p u r 1 o c k i^ ; and at the same time it 

 has been suggested that these fossils may represent the young of 

 Asaph us megistus, 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 

 (rerasaphes with the common Trenton 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 voung 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 

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

 have been found associated with Isotelus gigas-maxi- 

 mus (=megi9tus); facts which would suggest the specific 



» Am. jour. 8Cl. 1872. 3:426. 



