1896.] FISHES OF THE FAMILY GONORHYNCHID#. 501 
became the type of the genus Sphenolepis of Agassiz’, and was 
then referred to the Esocide. The Montmartre specimen described 
and figured by Cuvier was also placed in the same genus under the 
name of Sphenolepis cuvieri ; and since that date both these fishes 
seem to have been always quoted as related to the genus Esow. 
A recent examination of the specimens of these two fishes in the 
British Museum has now convinced the present writer that Cuvier’s 
original comparison of Sphenolepis cuviert with Gonorhynchus was 
correct ; that Sphenolepis squamosseus certainly belongs to the same 
genus; and that both these fishes are generically identical with 
Notogoneus osculus from the freshwater Green River Shales (Evcene) 
of Wyoming, U.S.A., which Professor Cope referred to the 
Gonorhynchide eleven years ago*. As the only surviving genus, 
Gonorhynchus, seems to be exclusively restricted to the seas border- 
ing Japan, South Africa, Australia, and New Zealand, the discovery 
of an extinct freshwater ally both in Europe and America is one of 
some interest. It is thus important that the principal osteological 
characters of the known fossils should be clearly stated to justify 
the comparisons made. 
1. Noroconrvs oscutus. (Plate XVIII. figs. 1, 2 
1885-86. Notogoneus osculus, E. D. Cope, Amer. Nat. vol. xix. 
p- 1091; Mem. Nat. Acad. Sci. vol. iii. p. 163, pl. with figs. 4, 5. 
Formation and Locality. Green River Shales (Eocene); Wyoming, 
U.S.A. 
The North-American form Notogoneus osculus has already been 
well described by Cope, who also publishes a diagrammatic figure. 
A beautiful new specimen, however, lately acquired by the British 
Museum, permits the determination of a few additional features. 
The head in this fossil, shown of the natural size in Pl. XVIII. 
fig. 1, is exposed directly from the side, and thus does not exhibit 
the hinder part of the cranial roof, which is fortunately well seen 
in the original specimen figured by Cope. The large and character- 
istic right frontal bone (fr.) is distinct, while the upper part of the 
otic region (ot.) is shown to be well ossified, and is evidently not 
entirely covered by the squamosal. The much-expanded hyoman- 
dibular (km.) is exposed, except at its lower end; but the other 
elements of the suspensorium, as also those of the pterygo-palatine 
arcade, are too much crushed and fractured to be distinguishable. 
The articulation for the mandible, however, is distinct below the 
front border of the orbit, and portions of both rami are preserved, 
that of the left side thrown upwards a little above the right ramus. 
Though imperfect the bones here indicated can readily be deter- 
mined by reference to the corresponding elements in the existing 
Gonorhynchus (P|. X VILL. fig. 5). The articulo-angular bone (ag.) is 
almost tan-shaped, extending upwards immediately in front of the 
articulation into a large, bluntly-pointed process. The dentary (d.) 
is much larger than the latter element, truncated in front, with 
very short oral border, and rising into an euormous upwardly- 
* Poiss. Foss. vol. v. pt. ii. (1844), p. 
2 American Naturalist, vol. xix. deeb) 4 p. 1091. 
