32 ' The Ottawa Naturalist. [May 



When this paper was written, the writer had not seen the 

 first part of Dr. Kossmat's memoir on the Chalk formation of 

 Southern India, pubhshed at Vienna in 1894, in which the sup- 

 posed A. /ukesti from Norris Rock is placed among the synonyms 

 of Lyioceras {Gaudryce? us) Kayei (Forbes.) On receiving a copy 

 of this publication, it seemed to the writer that the large and fine 

 specimens from Denman Island that had been referred to L.Jukesii 

 present several points of difference from the L. Kayei, as therein 

 figured, and one of the best of the Denman Island specimens was 

 sent to Dr. Kossmat, for comparison with the Indian species. 

 The conclusions arrived at on this point by Dr. Kossmat, after 

 this comparison had been made, and as embodied in a letter to 

 the writer, dated March 9th, i8g6, are as follows: 



"Your Lytoceras Jukesii must be distinguished from L. Kayei, 

 as you already supposed. "Specimens that are not full grown 

 (as that figured in Mesozoic Fossils, vol. i, pt. 2, pi. 13) agree re- 

 markably well with all the V^ludayur specimens seen by me, and 

 it would be quite difficult to distinguish them. "But, in the adult 

 state, the Denman Island specimens are quite different. "The body 

 chamber of L, Kayei, as shown in Plate 3, fig. 2, of my publication 

 is ornamented with very delicate striae, even thinner than in the 

 inner whorls, and of almost silky -appearance ; whereas, on your 

 L. Jukesii the ribs of the last volution become very strong and 

 sharp, and are separated by broad intervals. "There is no doubt 

 that such specimens are very similar to Lytoceras [Gaudryceras] 

 Jukesii, Sharpe, but considering the incompleteness of Sharpe's 

 type specimen, their identification with it will always be disputable. 

 "Judging from the figure and description of Sharpe's specimen, 

 the ribs of the type of L. Jukesii, in middle stages of growth, are 

 sharper, somewhat more distant, and not so strongly curved for- 

 ward on the sides ; the increase of the whorl in thickness is more 

 rapid, and the whorls are perhaps less numerous. "I think that 

 it will be be.st to give a new name to the fine specimens from 

 Denman Island. "Their septa are typical Gajidryceras septa, 

 with descending auxiliary lobes." 



The writer, accordingly, begs to propose for these specimens^ 

 which have already been described somewhat in detail and figured, 

 the provisional name of Lytoceras [Gaudryceras) Denmanense. 



Ottawa, April i6th, igoi, 



