NOUTHUMBERLAND A.VI) OrUHAM. 283 



CEPHALOrODA. 



35. NAUTILUS, Brryniiis. 



1. N. Frieslebeni, Geinitz. PI. XL, fig. '2Q)^juv. 



If, instead of dismembering this fine species, Mr. King had 

 endeavoured to trace its variations through all its periods of 

 growth up to the adult state, he would have deserved our Lest 

 thanks, and would have contributed something towards the full 

 understanding of its true character. But it has pleased him 

 better, instead of so doing, to represent and describe the young 

 of it as a new species, — N.. Boicerbankianus. The last chamber 

 only is the part principally represented of N. Friesleheni^ and 

 from it the characters of the whole shell, with the aid of Geinitz's 

 description, appear to be drawn; for the figure, pi. 17, fig. 16, 

 does not contribute much towards the elucidation of the species. 



If one examines the principal characters of Mr. King's new 

 species, viz., " deeply umhilkated ; ivliorls increasing rather rapidhj 

 in size ; slightly embracing (?) each other,''' it will be seen that they 

 are only the characteristics of young individuals; if they are 

 anything more, it will be necessary, in order to establish the 

 specific identity of N. BowerharJcianus, for Mr. King to represent 

 the young state and mode of growth of N. Frieslebeni, and show 

 in what points they differ. Until this has been done, it is better 

 to consider N. Boicerbanhiamis as the young state of the present 

 species. Here also must be placed the Naut. Theobaldi, Geinitz, 

 which, after examining a specimen, I could not distinguish from 

 the above. 



Very young specimens are much rounded in form, and orna- 

 mented with strong, decussated striai. The outer chamber of 

 Mr. Kirkby's largest specimen is nearly four inches in length, 

 and two and a half in greatest breadth. 



In the shell-limestone of Tunstall, Humbleton, Dalton-le-dale, 

 <S:c., and, according to Mr. King, in the compact-limestone of 

 Whitley. 



