350 (.'ONTRinUTIONS TO CANADIAN PALAEONTOLOGY. 



marginal a'lid cjccipital sulci, as well as upon the genal spines. The 

 occipital ring also is smooth, with the exception of a single circular 

 tubercle in the centre. Most of the prcjjecting part of the outer hcirdcr 

 is brokojL olf in the few specimens cnllected, and even when otherwise 

 uninjured its sui'face markings arp very badly preserved, though they 

 seem to have consisted of a single row of tuljc.rcles. 



Dimensions of the most perfect specimen collected : maximum Ijreadth 

 (jf head, H-'l'j nnn. ; length of the same, as measured in the median line, 

 fi-io nnn.; length of glaliella of the same, 4'-0 nnn. 



Lake A\'innij)egosis, on three small islands in the southern portion of 

 I)aws()n Bay, .1. 1!. Tyrrell, 1889 : tnur sjiecimens from one of these 

 islands and one from each of the otlier's. The specimens consist of nearly 

 perfect and fairly well pi-eserved detached heads, with the free cheeks in 

 place, but the summits (jf the eye-lobes of eacli specimen are broken off, 

 as are also the slender genal spines, with one excc]>tion, and the surface 

 ornamentatiun of the anterior bcjrder is very obscurely indicated. 



This little ti-ildbite seems to liavr much the same kind of surface 

 markings as the C. iirmifd of Hall* (from tlu^ Hamilton formation of the 

 State of New York) though the anterior border <.if the former niay prove 

 to lie spinos(^, when Ijetter preserved sj)eciiiiens shall have hieen collected. 

 The glabella and fixed cheeks of C. nriiaJd, howe\'e]', are represented as 

 being very much less convex than those of the present species. 



(S.) Proetus .-munduhis. (N. Sp.) 



Plate 4(;, tiys. 10 ami II. 



Oencr'al form narrowly suljelliptical, the length, as measured along the 

 median line, being .-diout twice the maximum breadth : surface depressed 

 convex, but distinctly trilobate, with a [irominent axis. 



Head nearly semicircular in outline, much broader than long, 

 rcjunded in front and broadest at the basi^ : characters of the genal 

 angles, and thost; of the genal spines, if thei'e were any, unknown. 

 Frontal area rather broad and llatteiied, margined externally by a very 

 narrow Ijut rather ]irominent u|)turned rim. Facial suture normal, 

 intersecting the anterior niargin almost in a, line with the most prominent 

 lateral porticai of e/ich eye. (Jlabella (lig. 11) modei'ately eonxcx, 

 distinctly defined and bounded cjn all siiles liy a narrow groo\-e, a 

 little longer than lnuad and l^roadesl, |)osteiiorly, o\ately subtriangu- 

 lar in oiitbne, but with the .anterior angle mcn-e bi'oadly rounded 

 than the postc-ro-basal ani^les, and the sides \-ery faintly constricteij at 



'P.ilitniit. St. N. V.irk, vol. A^JI, ISSS, ji. 1 ir,, plat<:s \.Ki, ti-. 1, and ,\xiv, tig. 2i. 



