Fossils of the Chazy Limestone, 467 



Cyrtoceras McCoyi, (N. s.) 



Description. — Of this species I Lave seen no specimens with the 

 smaller extremity preserved, and cannot therefore give the amount 

 of curvature. The best specimen is fusiform, nearly straight, and 

 two inches and a half in length. The section is oval, the greatest 

 (dorso-ventral) diameter at the aperture is eleven lines, and the 

 lesser apparently about eight lines. From the aperture the shell 

 gradually increases in diameter until at the first septum or at the 

 bottom of the bodv chamber, the dorsa-ventral diameter is 13 

 lines, and the transvesse diameter about 11. It then tapers to the 

 diameters of 6 and 5 lines in the next 18 lines of the length. 

 The ventral side is curved so as to form an arch, with a height of 

 three lines in a span of 1\ inches; the dorsal side is much more 

 gently arched. The septa are very gently concave, and one line 

 distant from each other. The siphuncle is moniliforra, 1 line in 

 diameter, and almost in contact with the shell on the ventral side. 

 Surface unknown. Differs from Cyrtoceras (Oncoceras) constric- 

 tion (Hall) in being proportionally more slender. 



Dedicated to the eminent Palaeontologist, Professor F. McCoy, 

 author of that excellent work, the British Paleozoic Fossils. 



Locality and Formation. — Chazy Limestone, Mingan Islands. 



Collectors. — Sir "W. Logan, J. Richardson. 



Crustacea (14 species). 



The trilobites of the Chazy limestone are usually found in 

 fragments; but the abundance of the remains shews that the 

 individuals were numerous. There appear to be about seventeen 

 species. 



Illamus Bayfieldii, I. ylobosus, I. clavifrons, I. arcturus, and 

 Amphion, Canadensis, have been already described : but besides 

 these there are the following : — 



Four species of Asaphus, one of which appears to be A. platy- 

 cephalus. 



Several fragments of a large species of Lichas. 



One species of Cheirorus } and part of a head, genus not deter- 

 mined. 



Bathyurus Angelini (N. s.) 



Description. — Oval, the posterior angles of the head produced 

 into short spines; length from one to two inches. 



