Prof. E. J. Chapman on new Trilobites from Canadian Rocks. 9 



Fig. 10. Filament bearing an older sporange. 



Fig. 11. Spore detached and quite ripe. It is still surmounted by a 



heterocyst. The transparency allows the enclosed spore to be 



distinguished. 

 Fig. 12. Germination. 

 Fig. 13. A young filament produced by germination of the spores. 



II. — On some new Trilobites from Canadian Rocks*. By E. J. 

 Chapman, Professor of Mineralogy and Geology, University 

 College, Toronto. 



I. On a new species of Asaphus from the Silurian Rocks 

 of Upper Canada. 



§ 1. Introductory Notice. — In the autumn of 1856, 1 commu- 

 nicated to the l Canadian Journal/ under the title of Asaphus 

 Canadensis, a brief notice of a supposed new Trilobite from the 

 Utica schist (Lower Silurian) of Whitby, in Canada West ; and 

 in a subsequent number of that publication, I gave a more de- 

 tailed description of the form. At the same time I pointed out 

 that Professor Hall of Albany believed it to be identical with a 

 species founded by him (under the name of Asaphus (?) lati- 

 marginatus) on two imperfect caudal shields, figured in the first 

 volume of his ' Palaeontology of New York/ At the period in 

 question, I was not in a position, from the want of works of refer- 

 ence and other sources of information, to claim this Trilobite 

 as actually new ; but an extended investigation having shown 

 it to be really a distinct form, — a view also adopted by others, 

 — I now publish a complete description of the species, together 

 with as accurate a figure as I am able to get executed in Canada 

 (seep. 13). In this communication, also, I have attempted to 

 show, by a brief analysis of all the fairly-established species of 

 the genus Asaphus, that our Canadian species is undoubtedly 

 distinct. I should state, with regard to the figures of Professor 

 Hall, alluded to above, that it is impossible to determine whether 

 our species be identical or not with these. In the words of 

 Barrande, in his great work on the Silurian Basin of Bohemia, 

 they are too incomplete to be determined with any certainty f. 

 For this reason, in the Museum of the Geological Survey of 

 Canada, the specific name of Canadensis, as originally bestowed 

 on this Trilobite by the author, has been retained. Barrande, 

 in the work just cited, alludes to another American Trilobite in 



* Communicated by the Author. 



t " Divers fragments d'Amerique nommes Asaphus par J. Hall, et figures 

 dans la Paleontologie de New York, sont trop incomplets pour etre sure- 

 ment determines." — Barrande, Systeme Silurien du Centre de la Boheme, 

 vol. i. p. 657. 



