238 ON THE PERMIAN CHITONID^. 



XX. — On the Permian Chitonidce. By J. W. Kirkby.* 

 Plate XIII. 



The discovery of Chiton Loftusianus at Tunstall Hill, in 1844, 

 by Messrs Loftus and King, introduced tlie Chitonidce into the 

 list of the Permian Fauna. For several years this species 

 remained its sole representative; but in 1856 another species 

 was found in the same locality, and in the course of the next 

 year it was described under the name of Chiton Howseanus.'\ 

 Until a recent date these were the only Permian species that 

 were known to belong to this group. In the present com- 

 munication, however, it is intended to describe four additional 

 members, three of which appear to belong to the subgenus 

 Chitonellus, and one, probably, to Chiton proper; so that, instead 

 of two, the Chitonidoe will have six representatives in the fauna 

 of the Permian epoch. The two species already known will 

 also be noticed, as a few characters pertaining to them seem 

 to have been overlooked in the descriptions and critical ob- 

 servations of which they have already been the subject. 



In the spring of the present year (1858), while pursuing 

 pal^ontological researches in the shell-limestone of Tunstall 

 Hill, I found some obscure fossils associated with specimens of 

 the Caly-ptrcea antiqua of Mr. Howse. For some time the true 

 nature of the former was a great puzzle to me; and it was 

 not until a month or two ago that I became aware of their real 

 affinities. Those to which I have alluded as being so very 

 problematical, I submitted to the inspection of my friend Mr. 

 Albany Hancock, who, when he had examined them, suggested 

 their relation to Chitonellus ; and having a specimen of the re- 

 cent species Chitonellus oculatus at hand, he at once removed its 

 plates from the mantle and compared them with the fossils. 

 We then saw the strong agreement of parts which existed 

 between these recent plates of Chitonellus and the fossils, and 



* Reprinted by permission (with some additions and corrections) from the Quart. Jour. 

 Geol. Soc, vol. XV., p. 607. 

 t Quart. Jour. Geol. Soc, vol. xiii., p. 216. 



