Raymond : Notes on Ordovician TRiLoiirrics. 



63 



as in aduk specimens of B. marginalis. From these characters it is 

 belicN'od that the small specimens called Asaphns alpha and gamma in 

 my previous paper are really only the young of marginalis. No adult 

 specimens of B. marginalis have been found with these small specimens 

 by the writer, but Hall's type was from the "crystalline and highly fos- 

 siliferous mass of the Chazy limestone, below the portion containing 

 Mad urea magna, at Chazy village," a description which exactly fits the 

 lavcrs from which these minute specimens were obtained. 



Fig. I. Basilicus marginalis (Hall). A pygidium, natural size, showing lobes 

 at the posterior end. 



It will be noted that these specimens correspond in many respects with 

 the minute trilobite described by Clarke as Gerasaphes ulrichana (Paleon- 

 tology Minnesota, Vol. Ill, pt. II, p. 710, figs. 14-16). The lobation of 

 the glabella is not the same, however, and Dr. Clarke states that the 

 surface of his specimens is smooth, not granulated. The specimens re- 

 corded as Gerasaphes ulrichana by Rucdemann (New York State Museum, 

 Bulletin 49, 1901, p. ( o) may well have been the same as the ones here 

 described, as there were a few Chazy species in the pebbles at Rysedorph 

 Hill. 



Genus Asaphus Brongniart. 



Subgenus Onchometopus Schmidt. 

 In erecting the subgenus Onchometopus for his species volborthi, Schmidt 

 placed a special emphasis upon the hooked character of the doublure 

 of the front of the cephalon, but there are other peculiarities which make 



