OF THE COUNTIES OF NORTHUMBERLAND AND DURHAM. 231] 
VERTEBRATA. 
Cuiass. PISCES, Linneus. 
Orper GANOIDES, Agassiz. 
Famity Leprporpss, Ag. 
1. PALZEONISCUS, Ag. 
1. P. comtus, Ag. 
Paleoniscus comtus, Ag., Poiss. Foss. ii., p. 97, pl. 10 b, f. 1-3. 
Paleothryssum magnum, Blainv., Geol. Tr. 2nd ser., iii., 
Paulie ply sy bel 
Palcothryssum macrocephalum, Blainv., Geol. Tr. 2nd ser., 
aI Duell fanple9, tera. 
In the Marl-slate ; not uncommon. Whitley, Cullercoats, 
Boldon Hill, Quarrington Hill, Ferryhill, East Thickley. 
Of all the fishes which occur /in the Marl-slate, the P. comtus 
is the most common and characteristic species. “The head is 
about one-fourth of the whole length of the body ; all its bones 
have the outer surface marked with points disposed in irregular 
rows. ‘The pectoral fins are of a moderate size, but proportion- 
ally larger than the ventrals, the anal, and the dorsal. The 
tail is large, but its rays are less slender and more bifurcated 
than in the following species. The transverse articulations _ 
of the rays of this fin are also more distant, but those of the dor- 
sal and anal are less than in P. elegans. The scales vary consi- 
derably in size and form, according to the part of the body 
which they occupy. Those of the flank are largest, they are 
higher than wide, and all their surface is ornamented with fur- 
rows and very close punctures, which are nearly parallel, and 
which terminate on the posterior side in a finely serrated margin. 
The superior side of the scales is concave, and the inferior con- 
vex. The scales of the upper lobe of the tail become more elon- 
gated as they approach towards the extremity. In addition to 
these characters, it will be easy to distinguish this species by its 
