REMAINS OF REPTILES AND FISHES. 97 



present; and both the tail and fins are frequently determinable. 

 Several of them are probably new ; but at present we cannot 

 enter more fully on this branch of the subject, and must leave it 

 for some future opportunity. A few words, however, may be 

 said on the dentition of these fishes, particularly as it seems to 

 be little understood ; indeed it appears that little or no attention 

 has been given to this matter. 



M. Agassiz, in his great work, " Poissons Fossiles," states 

 that the teeth of Palceoniscus are "en brosse" (tome ii., pt. 1, 

 p. 42) ; but the words which immediately precede this expression 

 must be taken to qualify it. They are — " Mais les dents sont si 

 exeessivement petites qu'il est tres-rare de pouvoir les distin- 

 guer." From this it is pretty evident that this distinguished na- 

 turalist knew very little about the matter. Succeeding writers, 

 however, appear to have rested satisfied with this description. 

 Mr. Binney, indeed, so long ago as 1841* figured the jaw of 

 PalcBoniscus Egertoni, showing a row of large, conical, sharp- 

 pointed teeth, as well as a few of the small external ones. He 

 says that the jaw is " armed v/ith sharp conical teeth of a nearly 

 uniform size, inclining from the front." This communication, 

 however, has been unfortunately overlooked. 



The teeth of these jaws are not " en brosse," neither are they 

 of that feeble "villiform" structure so much insisted on of late. 

 They are disposed in two distinct rows, one within the other, 

 much in the same fashion as in Megalichthys and Rhizodojysis, 

 but still much more like that which obtains in Pygopterus, in 

 which the teeth are likewise arranged in two rows — one being 

 of large laniary teeth, the other of small external ones. And, 

 according to M. Agassiz, they do not in this genus form "une 

 brosse ou rape comma les dents du Pohjplerus." The inner row 

 in PalcEonhcus (Plate II., figs. 3, 4, 5) is composed of a few 

 comparatively large, curved, sharp-pointed, conical teeth, which 

 are placed at some little distance apart from each other. In the 

 outer row the teeth are numerous, small, conical, and pointed, 

 occasionally crowded, and in some species apparently not quite 

 in regular order. 



♦"Transactions Manchester Geolopiral Soci.iy," Vol. I., r- If"!", Pl'ite V., fig. 12, ISll, 



G 



