260 MESSRS. HANCOCK AND HOWSE 



is modified ; and in this interesting form we see, for the first 

 time in the geological series, a true thoracic, or rather a true 

 jugular fish of the Linnean classification ; for the ventral fins 

 are considerably in advance of the pectorals, and, indeed, they 

 are placed as far forward as it is possible for them to be. Some 

 change in the body-scales might therefore be expected, though 

 the fins have the usual structure of those of the group to which 

 this fish belongs ; and the tail is decidedly heterocercal, with the 

 lobes, which are deeply forked, of nearly equal length. And in 

 the upper lobe there is a double row of the usual rhomboidal 

 scales, resembling in their form and mode of articulation those 

 on the tail of Acipenser Sturio, Linn. No other scales are ob- 

 served on any part of the body of either of the four specimens, 

 unless, indeed, the ventral and sigmoidal plates be so considered. 

 We have, then, in Dorypterus a ganoid fish not only deprived of 

 body-scales, but without plates of any kind except those just 

 alluded to. 



Having now given the result of a very careful examination of 

 all the four specimens at our disposal, collating and rigorously 

 estimating the facts exhibited by each, we shall now give sepa- 

 rate descriptions of the specimens themselves, marking empha- 

 tically the points for which each is distinguished. 



The first specimen (PL X., fig. 1) that we shall notice is from 

 the cabinet of our friend Edward Wood, Esq., Eichmond, York- 

 shire. It is four inches long, including the tail, and is about 

 one inch and three-quarters deep at the deepest part. The an- 

 terior portion is well preserved. The head is one-third of the 

 entire length of the fish, exclusive of the tail-lobes, and is one- 

 third higher than long ; it is arched in front, being most protu- 

 berant at the muzzle ; behind, it is angulated near the centre, 

 the posterior margin of the operculum (s) determining the form ; 

 the jaws (p, q) are nearly perfect, and are closed, showing that 

 the mouth shuts upwards ; the maxilla is wanting, only the im- 

 pression of it remaining, indicating its form and position. The 

 brow, orbit (u,) gill-cover, and clavicle (r), are all in their na- 

 tural positions, no considerable disturbance of these parts having 

 taken place. 



