CANADIAN FOSSILS. 89 



We dedicate this species to Professor J. Hall, the distinguished 

 palaBontologist of the New York survey.* 



Locality and Formation. — Trenton limestone, City of Ottawa, and 

 Lake St. John. 

 , Collectors. — Sir W. E. Logan, E. Billings, J. Richardson. 



II. Cyclocystoides Davisii, Salter. 



C. ovalis ? uncialis et ultra, ossiculis marginalibus 48-49, co?^^'6'a;^.?, Icevigatis, 

 extiis profande excavates, simplicibus nee radiatim bilobis, margini recurvoi 

 siqjerficie obscure 8, radiato. 



This species certainly differs from the American one in that the 

 number of marginal ossicles is much greater (forty-eight or forty-nine), 

 while the ossicles themselves, instead of being granular, are smooth, 

 and have the outer division much deeper, the margin being produced 

 upwards as a distinct rim. Neither the division of the ossicles in 

 this outer portion into two lobes, nor the separation of one ossicle 

 from its neighbour, is at all distinctly marked ; but just at the base 

 of the deep excavation short-raised ridges indicate faintly these 

 divisions, while the annular pits at the bottom are still deeper and 

 more distinct than in the C. Halli. 



This species shews the complete surface, on which about as many 



* Professor Hall in 1851 described a species of this genus in the pala3ontological part 

 of Foster and Whitney's Report on the Geology of Lake Superior, page 209. Each of 

 the specimens which he figures (see plate xxt. fig. 4, a, b, c, of the work cited) exhibits 

 twenty-nine marginal plates. The smallest of ours (plate s. figure 5 of this decade) 

 although exactly the size of the largest figured by Prof. Hall, has thirty-six, and so have 

 our two largest. The Escanaba specimens are therefore most probably of a different 

 species, which has not yet been named. The following is Prof. Hall's description : — 



" This body consists of a ring, or a sac, the upper edge of which only appears, 

 composed of numerous j)lates joining by their broader edges. The upper or exposed 

 surface of the plates is sculptured or granulated, convex, and not closely joined together 

 at the upper angles, presenting the appearance of somewhat quadrangular tubercles ; 

 exterior margin of each plate furnished with a thin wing-like expansion, marked by two 

 diverging ridges. 



" This curious body is evidently Crinoidean, from the character and structure of the 

 plates. The ring presents an appearance very similar to the row of plates surrounding 

 the valves which close the ovarian aperture in some Cystideans, but the number is far 

 too great, being in one specimen twenty-nine, and apparently not less in the other. 

 The inner faces of the plates moreover do not present any appeai'ance, as if for the 

 attachment of other plates or valves. It is possible that it may be the elevated 

 marginal ring of some one of the sessile Crinoids, though the arrangement of the plates 

 is more regular than in any species known to me. 



" Locality. — Banks of the Escanaba river, two miles below the mouth of Indian 

 creek, in the Trenton limestone." 



