Gunther—Plinthophorus robustus. 115 
examined in the British Museum, do not show sufficient traces 
of the fins, by which their form or position could be ascertained ; 
but there is a fragment of another large example in the British 
Museum, in which some of the dorsal rays are well preserved, 
and which confirms the generic character derived by Agassiz 
from the dorsal fin. ‘The rays are short, slender, wide apart, 
and simply bifid at the extremity. The vertebree of D. elongatus 
also are very different from those of this specimen, their central 
part being perfectly smooth and polished, whilst it is very rough 
and longitudinally grooved in the specimen before us. Pictet 
(Poiss. foss. Mont Liban., pp. 46, 47) describes three other 
species of Dercetis; and there can be scarcely any doubt that 
he is correct in referring them to that genus, and consequently 
that they are different from our Fish. 
As regards the second genus Rhinellus, the characters origi- 
nally given by Agassiz (ic. p. 260) have been rectified by 
Pictet (Zc. p. 43). It agrees, then, with our Fish in having a 
short dorsal fin, nearly in the middle of the total length, above 
the nine- or ten-rayed ventral fin. Whether both ought to be 
referred to the same genus is impossible to decide, partly on 
account of the imperfect state of the specimens of Rhinellus 
furcatus, partly on account of the total want of evidence as to 
the form of the head and jaws in our specimen. The probability 
is that they belong to different genera; for, whilst Rhinellus is 
described as having three series of bony plates on each side, 
this has only two; the dorsal fin of the former is placed more 
backwards; and the specimens known have only a length of 
three or four inches, and are from the Lebanon. Finally, as 
regards the Rhinellus nasalis of Agassiz, or Pegasus lesiniformis, 
our knowledge of it rests, at present, solely with the rude figure 
of the ‘ Ittiolitologia Veronese’ (pl. 39, fig. 1), from which we 
do not obtain any further information than that it is a fish 
similar to Rhinellus furcatus. 
We proceed to characterize the genus which we propose for 
our fossil, and to add a detailed description. 
PLINTHOPHORUS,* gen. nov. 
Body oblong, apparently scaleless, but with a dorsal and ventral 
series of imbricate, arrow-shaped, osseous scutes on each side. Dorsal 
fin rather short, placed in the middle of the total length, above the 
ventrals ; anal short, at some distance behind the dorsal; caudal 
fin forked, Pectorals and ventrals well developed, without osseous 
spine, the latter nine- or ten-rayed. 
Plinthophorus robustus, spec. nov. 
The vertebral column is nearly entirely preserved, only the verte- 
* Derived from mAwOopdpos, bearing tiles. 
I 2 
