422 Description of a new Trilohite, 



reference be correct, then we have at least three, if not four spe- 

 cies in North America. 



1. C. antiquatus (Salter,) described from "a cast in a brown 

 sandstone, said to be a bouldered fragment from Georgia." (See 

 Quart. Jour. Geol. Soc, vol. xv, p. 554.) 



2. C. minutus (Bradley.) In this species, the form of the 

 glabella and its proportions in relation to the length of the head 

 are almost precisely the same as in G. antiquatus, and yet I think 

 the two are not identical, for the following reasons : In the first 

 place, all the specimens of C. minutus are of a nearly uniform 

 size, the length of the head being about two lines, and, therefore, 

 it seems probable that they are the remains of adult individuals. 

 The total length would thus be about half an inch, while Mr. 

 Salter's species is full one inch and three-fourths. In the second 

 place, the distance of the eye from the glabella, in G. antiquatus 

 is only one-third the width of the glabella, but in (7. minutus it 

 must be at least one-half the width. These are the only differ- 

 ences that can be well made out, from the imperfect specimens, 

 but they seemed to me sufficient to indicate two species. Mr. 

 Salter says further, that the lobes of the glabella in G. antiquatus 

 are very obscure, and that the ocular ridge, if any existed, must 

 have been very slight. His specimen was somewhat abraded* 

 In C. minutus the ocular ridge is, for so small a species, very 

 strongly defined, and the glabellar furrows are so deep that it 

 would require a very considerable amount of abrasion to obliter- 

 ate them. 



3. G. Zenkeri, (n. sp.) This is a new species recently discov- 

 / ered in the magnesian limestone near Quebec. It will probably 



*^ be described in the next No. of the Canadian Naturalist and 

 Geologist. 



4. There is in the collection of the Geological Survey of Canada, 

 a plaster cast of the surface of a fragment of rock which holds 

 four specimens of a trilobite, each about the size of G. antiquatus. 

 They appear to me to belong to the genus Gonocephalites. The 

 original specimen was collected in Newfoundland, in the same 

 slate that holds Pradxides Bennettii (Salter,) and I am informed 

 that it is in the possession of a gentleman who lives somewhere 

 in the United States, but whose name or place of residence, I have 

 not been able to ascertain. 



Of the above four species, Mr. Bradley's is at present the most 

 important as it fixes indisputably, at least one point in the geolo- 



