208 P. E. Raymond — Ceratopyge Fauna 



front, and expands forward in the typical Ceratopyge. 

 The Canadian form has no glabellar furrows, while C. for- 

 ficula always shows at least the posterior pair. A most 

 important difference is in the course of the facial sutures 

 in front of the eyes. In C. forficula they diverge and 

 quickly intersect the margin, whereas in C. canadensis 

 they turn but little outward, then inward, so that the 

 anterior part of the cranidium is pointed, as in Isotelus. 



The position and origin of the spines on the pygidium 

 are fundamentally different from those of Ceratopyge. In 

 C. forficula these spines are, as Dr. Walcott has said, the 

 continuation of the second segment, but they are firmly 

 welded into the pygidium, so that they appear as projec- 

 tions of the margin. In C. canadensis the spine-bearing 

 first segment of the pygidium is so nearly severed from 

 it, that it would be almost as true to say that the last seg- 

 ment of the thorax was laterally extended into spines, as 

 that the first one of the pygidium was spinose. 



It is difficult to place this trilobite. The general aspect 

 is that of the Asaphidae, and were there not 10 (or 11) 

 segments in the thorax, one would be inclined to refer it 

 to Asaphellus. The most nearly allied form which I have 

 seen described seems to me to be Dolichometopus (Housia) 

 varro Walcott, from the Upper Cambrian of the House 

 Range in Utah. 14 This trilobite is, unfortunately, itself 

 imperfectly known and of uncertain affinities. 



In order to avoid giving a new generic name, however, 

 I would suggest that the trilobite from the Goodsir be 

 called Housia canadensis , unless it can be shown to be 

 generically distinct from the type of Housia: — neither is 

 very suggestive of Dolichometopus. 



In the Robson Peak district on the border between Brit- 

 ish Columbia and Alberta, Walcott 15 has referred the 

 Robson limestone to the Ordovician and found at the base 

 an assemblage in which "there is a commingling of the 

 lower Ordovician and Upper Cambrian faunas." From 

 Billings' Butte, north of Mount Resplendent, he has 

 identified, among others : 



Eoorthis desmopleura (Meek), Syntrophia nundina Walcott, Agnostus sp., 

 Triarthrus sp. ind., Peltura (pygidia), ApatoTcephalus, and two species of 

 Illaenurus [Symphysurus]. 



14 Smithson, Miscl. Colls., vol. 64, p. 374, 1916. 



15 Smithson, Miscl. Colls., vol. 57, p. 336, 1913. 



