liutclut fl 



TRILOni 



701 



18 subserved in the ratontiOQ Of this nann 1 . Knr purposes of comparison a copy of 

 l>alman' ti^nro of As'i^lnis t -j-jinsit^ i- lien- introduced. 



Flu*. 4. Outline of Atayhu* trpanmt WahU-nU-iy (afu-r Dalnian). 



ISOTELUS oioAs DeKay, 1824. 



luxgigan I>rK \v |8M. AtinaN Ly.-.-uin Nat Hist. N. V., rol. I, p. 174, pi. 12, fitf. I, pi. 13, tg. 1. 

 Ataphut }ilntycrj>halu* (STORKS) of mewl authors. 



ISOTBLUS MAXIMt'S Locke, 1838. 



.:, 1838. Second Aon. Kept., Oeol. Surv. Ohio, p. 246, flgn. 8, 9. 

 /"trim m'aittn* I.IM KK, 1841. Trans. Amer. Aaooc. Oeol. and Nat. p. 221, pi. 6. 



Ataphu* nuyi*tu* I L<x KK) of m)8t authors. 



Iii referring to these two widely known trilobites under the same caption, it is 

 not the intention to assume their specific identity. It is, however, on many accounts 

 ci m venient to consider tlicin together, as careful study of a large series of both forms 

 has elicited some important suggestion concerning their mutual relations. 



The usual basis of distinction between these contemporaneous fossils is an 

 exceedingly simple one. i 'mi-tructed upon essentially the same specific type, the one, 

 /. 'jiyas, is devoid of cheek spines; the other, /. maxinnu, possesses them. It is hardly 

 necessary here to enter into a detailed account of the characters of these fossils. 

 They have been given at length l>\ various authors, Hall. 1 Hurmeister,' Meek, 1 

 Miller. 4 and others. 



In the original specimens the conventional distinction l.ctween the species was 

 clearly indicated. DeKay's figures, one of an enrolled example, one of an extended 



(IT PlOfitoUj of N.-w Y.,rk. v.,l [. p ill. pl.tM .!., O, I- 17 



ontanltalloa of tb TrilohltM < R*r > ..UHon i. p. 110, pi. 1 (. U, IMS. 



(*. Palamatolor "' Ohio. rol. I. p. 159. pi. II B. 



D.-lnn.ti yu.ru Juurn. Scleor-. ol. I. pp. 7, l> 



