Tkilobuks ok thk Chazv Llmf.stonk. 329 



Harpes antiijnatus Hillings, Remipleiirides canadensis Billings, 



Ilheniis arctunis Hall, SpJucrexochus parvus Billings. 



Of these species, Asaphus caualis, Asaplins platyccphahis, and Illcc- 

 niis crassicauda / are doubtfully identified, as was admitted by Mr. 

 Billings. Tllicnus arctunis, Illtrnus vindex, and Illo'.niis clavifrons are 

 synonyms for Thaleops fli'atus, and Cheirurus prolificus is a synonym 

 for Pscudosphccrexochus vulcanus, thus reducing the list to thirteen 

 identifiable species, making sixteen good species in all up to the end 

 of the year 1865. 



Brainerd and Seely, who were the next to take up serious work on 

 the formation, paid most of their attention to stratigra])hy, and by 

 wonderfully accurate work in a much faulted region showed, that, in- 

 stead of three hundred feet of Chazy, as had been previously estimated, 

 there were from seven to nine hundred feet in the typical region. 

 They collected many fossils, but beyond a ])reliminary identification 

 they did little with them at the time. Professor Seely in 1885 and 

 1902 described several species of sponge-like forms, but did not add 

 to the list of trilobites. Brainerd and Seely did, however, send 

 specimens to Professor R. P. Whitfield, who described a few new 

 species (18S1). Among them were two trilobites, Lichas chanip/ain- 

 ens/'s, founded on a pygidium, which probably belongs to the same 

 species as Billings' cfi]}\\2i\o\\oi Lichas mi nj^anen sis, and Sao ? Lanwt- 

 tensis. Walcott had, however, described a cranidium of this latter 

 species in 1S77 under the name ArioneUus pustulafus, so that both of 

 Whitfield's names become synonyms. Thus ArioneUus pustulatus 

 Walcott is the only new species of trilobite added between 1865 

 and 1904, making a total of seventeen recognizable species at the 

 present time. 



As is known to all students of the ()rdo\ician, these species are 

 described from very fragmentary material, and the early reports of the 

 Canadian Survey are out of print and difficult to obtain. For this 

 reason the writer proposes to redescribe and refigure all the old spe- 

 cies, in order to make them available to students, and, at the same 

 time, a review of the fauna has brought to light some eighteen forms 

 not hitherto known to occur in the Chazy, thus doubling the trilobite 

 fauna. 



The collections on which this review is based have been accumu- 

 lated by the writer during five season's work around Chazy, Valcour 

 Island, and Crown Point, New \'ork. A part of this collecting was 



