86 NEW YORK STATE MUSEUM 



described as possessing the same number of longitudinal ribs within the 

 same space, the same cancelation in some parts, but has somewhat deeper 

 camerae, tapers slightly faster and is perfectly straight. This species is said 

 by Hall to be identical with the numerous species of longitudinally ribbed 

 Racine forms erected by McChesney, and also with Hall's O. v i rg a t u m (?) 

 and O. cancellatum from the Rochester shale of New York. Whiteaves 

 identifies the latter species with Orthoceras cadmus Billings, which 

 has been described from the Niagaran at Grimsby Ont. 



Kionoceras medullare Hall (sp.) 



Plate 10, fig. 23 



Orthoceras medullare Hall, Geol. Sur. Wisconsin. Report of Progress. 1859. 

 Orthoceras medullare Hall, N. Y. State Cab. Nat. Hist. 20th An. Rep't. 1867. 



p. 353, pi. 20, fig. 1, 2 

 Or th oc eras m ed u liar e (?) Meek & Worthen, Geol. Sur. Illinois. 1875. 6:504, 



pi. 26, fig. 1 

 Orthoceras medullare Whiteaves, Paleozoic Fossils. 1884. v. 3, pt 1, p. 37 



This species is represented in our collections by a single mold of the 

 exterior from the lower Shelby dolomite. The ornamentation of this 

 fragment, which belonged to a conch having a diameter of about 30 mm, 

 consists of sharp, longitudinal striae, alternately stronger and finer ; these 

 are crossed by transverse lines, arranged slightly closer than, and equal 

 in prominence to, the finer, longitudinal striae. Seven of these longi- 

 tudinal lines may be counted in 10 mm. The character of this ornamenta- 

 tion, the relative distance and strength of the striae, is that ascribed to 

 O. medullare, and we, therefore, provisionally identify the Shelby 

 species with that. 



Hall described Orth. medullare from "limestone of the Niagara 

 group at Waukesha and Wauwatosa, Wisconsin." In the lists of fossils of 

 Wisconsin, given in Geology of Wisconsin, v. 2, K i o n. medullare is 

 cited only from the Waukesha and Racine beds, but not from the Guelph. 

 Meek and Worthen doubtfully refer to the species a specimen from the 

 Niagara at Joliet 111. Whiteaves reports the species in the Guelph at 

 Elora Can. 



