ii.i'i.n i 



fiinii.-. 'I'u indicate to tin- -tti.: . collector t lie -t i u.-l ure <>! tin- cut in* 



.1111111:1! I iiitni'lurc ;i iL'tne drawn tnun . pecimei. 



! 



i'i 'ii \\'nli-ii/t, (.-p.) 1^77. 



. 



tntormeditu \N \ 8fl ll. -!.. p. . 



Mr. Walcnr- ies has not heretofore been figure*!. Imt, after careful compai- 



i-on witli tin- de-cription. ami with the ;iiil of the original specimen, I have little 

 hesitation in referring to it the commonest of the lining 



in the Silurian rock- of Minnesota. Without entering intoa detniile'l ilr-crijition of 

 llii^ form, which has been given l>y Walcott, some of its diflerentiul features may 



mphaoii 



The outline of the cephalon is rendered sulitrian^ular Ity a slight anterior 

 |inijection of the margin. The facial -utiires al>o 11; -ightly salient angle at 



thi- ['uiiit, ami fre ( |iient ly here the surface of the glabella i> impressed or casually 

 force. I ilown. The anterior limli- of the suture cut oil or traverse the lateral angles 

 of the frontal lol.e. as in all species of / <iopus; the posterior extension of 



k- i- marlu-.l liy an I line. The eyes are relatively 



-mall, their anterior a ; iin;r the lir-t L'laliellar furrows, while their 



frointh ..... -i-ipital furrow. The gliiliella i- cliarai-tei 



'ie slight anterior or ontwanl con. .teral furrows, the graceful 



mlity of all the 1. .---e.l, though -lightly convex 



median region l.etweeu the tirst and seroml pair- of lateral lohes. <>n a.-.-mint of 

 this depression the lol- ,ite i-o|.ite.l an.) not conlli !i the middle iif the 



glaliella. The second furrows are linear, deep only at their proximal extrem 

 Imt di.-tim-t ly continue*! to the dor-al furrow-. The third or occipital lol.e- are -mall 



