238 ON SOME NEW TRILOBITES FROM CANADIAN ROCKS. 



angles are unknown — by its thorax and pygidium being of equal or 

 nearly equal length, and by its divided glabella. 



M. de Verneuil's species, A. Barrandei, from the south of France, 

 is only known to me Tby name. Reasoning from analogy, however, it 

 may be fairly admitted' that the two species are distinct. 



Our new Canadian species somewhat approaches Barrande's Asaphus 

 nobilis, by the curious transverse furrow on its glabella. In A. nobilis, 

 however, the genal points of the head-shield terminate in horns, and 

 the segments of the thoracic and caudal axis are marked by peculiar 

 furrows, characters not exhibited by the present species. The trans- 

 verse furrow on the head-shield probably corresponds more or less in 

 outline with the underlying hypostoma, but no traces of the latter 

 organ, as already remarked, have yet been found. 



In th,e preceding article on Asaphus Canadensis, it was stated that 

 Professor Hall had published, in the first volume of the " Palaeon- 

 tology of New York, two imperfect caudal shields, under the name of 

 Asaphus (?) Latimarginatus. I would willingly adopt this specific 

 name for our second Canadian form, because, so far as it is possible to 

 determine, the two may prove eventually to be alike ; but, on due con- 

 sideration, I have thought it advisable to bestow upon the form in 

 question a name altogether distinct. My object in this, is solely to 

 avoid thQ chance of confusion, in case the thorax and head-shield of 

 Professor Hall's form should hereafter be discovered, and be found on 

 examination — -as would very likely happen — to constitute a different 

 species. I therefore claim the privilege of naming the trilobite de- 

 scribed in this article, a privilege to which I am justly entitled by the 

 really indefinite character of the figures referred to above. The name I 

 adopt as the most appropriate, under the circumstances of the case, is 

 that of Asaphus Halli. Palaeontologists, I am sure, will receive it 

 willingly.* 



* The author's best thanks are due to his colleague the Rev. Professor Hincks, as well as to 

 John Head, Esq., and J= P. Smith, Esq. of Toronto, for the loan of specimens of Asaphus 

 Canadensis. He has also to express his obligations to the Rev. Yinccnt Clementi of Peter- 

 borough, Canada West, for a specimen of Asaphus Halli. 



