ON DOEYPTEEUS HOFFMANNI. 263 



plane with the similar aspect of the other plates. The lower 

 margins of the two sets are in. close contact, the line of junction 

 coinciding with the ventral margin. The plates in both series 

 incline forwards, their pointed extremities being turned back- 

 wards ; and the compound columns (n) in connexion with the 

 upper extremities are distinctly displayed, those belonging to 

 the left side taking their usual course upwards in the direction 

 of the head and lozenge-shaped area, those on the right side, or 

 those of the displaced series, passing outwards from the speci- 

 men, the columns, like the plates themselves, having being dis- 

 placed and thrown downwards. And thus we have a satisfac- 

 tory proof that both the ventral plates and columns are developed 

 in two lateral and distinct series. And furthermore, these co- 

 lumns are seen, in the specimen before us, to pass upwards and 

 become united to the lower anterior lateral plates, notwithstand- 

 ing that they are much disturbed at this point. 



The dorsal fin («) has been broken away, only three-quarters 

 of an inch remaining. The anterior basal extension, however, 

 is well shown, as this portion is turned a little towards the ob- 

 server, and has been forced downwards. Consequently the 

 short anterior basal plates, or fin-fulcra («"), are seen to be ar- 

 ranged in a bilateral series of about twelve. This bilateral ar- 

 rangement of the fin-fulcra is not, we believe, usual among the 

 ganoids, in which the two lateral halves are commonly united 

 into one piece. Mere traces are observable of the narrow pos- 

 terior extension of the fin, though the marginal hour-glass- 

 shaped plates are regularly disposed immediately within the 

 posterior slope. Nothing is to be seen of the anal fin, except 

 the base of the anterior portion, at which point the hour-glass- 

 shaped plates are distinctly displayed ; and traces of them are 

 visible almost to the tail. The remains of both ventral fins (d) 

 are traceable immediately in front of the ventral plates, over the 

 anterior of which one of them is spread, the rays being directed 

 backwards. 



The tail is admirably shown, and is exceedingly perfect. The 

 lobes are expanded, exhibiting the depth of the bifurcation. The 



