Notes on Rii'lniioiid iiiid lirlnlcd Fossil.f 51 



of the ])laster casts. To all of these eminent paleontologists I 

 am greatly indebted for these courtesies. Specimens of Orthis 

 rcirorsa, from anything near the type locality, are exceedingly 

 difhcnlt to obtain, and the specimens here illustrated represent 

 practically all of the known material available. 



Zitteloceras hallianum, D'Orbigny 

 Plate III, Figs. 5 A, B 



1847. ("vrtoct-ras lanicllosum. Hall (not Verrieuil, 184'-2), Pal. New York, 



" 1, p. 93, pi. 41, tigs, i ii-c. 

 1849. Cyrtoceras hallianu.s, D'Orbigny, Prodr. Pal., 1, p. 1. 



The type of Cyrtoceras lamellosum, Hall, numbered 8'23, 

 is preserved in the American Museum of Natural History, in 

 New York City. It is a fragment 23 mm. long, and of this 

 length about 10 mm. belongs to the body cavity. This is fol- 

 lowed by five chambers occupying a length of about 5.5 mm. 

 The width is slightly greater than the length, the width at the 

 l)ase of the body cavity being 11.5 mm., and the antero-pos- 

 terior diameter 9.5 mm. The rate of tapering tow^ard the apical 

 end is small, the lateral diameter at the smaller end of the 

 fragment being 9 mm. The surface is ornamented by rather 

 distant sharp, undulate, transverse, squamose lamellae. Of 

 these there are eight in a length of 10 mm. Along the median 

 part of the ventral side these well defined transverse lamellae 

 are curved strongly toward the apical end for a distance equal 

 to about the distance between the lamellae. Originally these 

 lamellae may have extended for a distance of about half a 

 millimeter from the general surface of the cy rtoceracone ; 

 they evidently represent stages of grow^th. Laterally, these 

 lamellae undulate in a series of scallops, as indicated on the 

 upper left-hand part of the accompanying illustration, figure lA. 



The type was obtained in the Trenton limestone at Middle- 

 ville, New York. 



It is evident that Cyrtoceras hitzi, Foerste (Deni.son Univ. 

 Bull. XVI, 1910, p. 78, pi. I, figs. 7 A, 15; pi. II, figs. 23 A, 

 B, C), from the ujipermost Richmond strata exposed at Mad- 



