of Fishes referrible to the Genus Chimera. e 
the dental edge truncated and square; the superior maxillary 
is irregularly triangular, much elongated, and contracts in- 
sensibly towards its dental extremity, which is bifid. 
In the Chimera Agassizii of Dr. Buckland the inferior 
maxillary is the most regular in form of the four species; it is 
nearly square, and has the dental edge slightly open; the sur- 
face of the symphysis is flatter than in the other species. 
The Chimera Mantellii has the inferior jaw straighter and 
thinner: its exterior surface is perfectly smooth and flat; its 
snout is much elongated and pointed, and the cavity of the 
dental edge wider. 
Since Dr. Buckland’s discovery of the above four species, 
I have found a fifth in the collection of Mr. Greenough, which 
differs considerably from them all, in the extreme shortness of 
the lower jaw, the length of which is less than its height. 
The symphysis of the lower jaw is flat; the dental margin 
truncated and grooved in its hinder part. The external sur- 
face is smooth; the middle of the inner surface concave; the 
intermaxillary is flatter than in the Chimera Egertonii, and 
terminates in a straight point. The superior maxillary is 
shorter than that of the Chimera Egertonii. 
I propose to give to this species of so remarkable a genus 
the name of Chimera Greenovii. The locality of this fossil 
is unknown. 
Oxford, Oct. 27, 1835. 
III. On the Relation between the Velocity and Length of a 
Wave,.in the Undulatory Theory of Light. By Joun 
Tovey, Esq. 
To the Editors of the Philosophical Magazine and Journal. 
GENTLEMEN, 
[X the last volume but one of your Magazine, the Rev. Pro- 
fessor Powell presented us with an abstract of the essential 
principles of M. Cauchy’s View of the Undulatory Theory of 
_ Light; by which, as Mr. Powell says, it appears “ that a rela- 
tion between the velocity and length of a wave is established 
on M. Cauchy’s principles, provided the molecules are so 
disposed that the intervals between them always bear a sensi- 
ble ratio to the length of an undulation.” vol. vi. p. 266. 
Since I first read this, I have arrived at the same result as 
M. Cauchy by a less complicated method, which I proceed 
to lay before you. Ido this with diffidence, having read 
scarcely anything on the subject besides the abstract above 
mentioned and Professor Airy’s tract. Should you deem 
