ETJGNATHIDjE. 
291 
Eugnathus orthostomus, Agassiz. 
[Plate IV. fig. 1 ; PI. V. fig. 1.] 
1825. Lepidosteus? dentosns, C. Koenig, Icon. Foss. Sect. pi. xii. 
fig. 140. 
1842-44. Eugnathus orthostomus, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. 
p. 98, pi. lvii a . 
1839-44. Eugnathus speciosus, L. Agassiz, ibid. p. 100, pi. lvii. [Head 
and scales ; Oxford Museum.] 
1844. Eugnathus scabriusculus, L. Agassiz, ibid. p. 105 (name only). 
[Jaws, etc.; British. Museum.] 
Type. Nearly complete fish ; British Museum. 
The type species, attaining a length of about 06. Length of 
head with opercular apparatus equalling about one-quarter, and 
maximum depth of trunk about one-fifth of the total length of the 
fish ; minimum width of caudal pedicle equalling half the maximum 
depth of the trunk. Head elongated, the roof of the skull being 
about three times as long as its width at the occiput, and all the 
external bones smooth or with few small tuberculations ; hinder 
two-thirds of maxilla bearing comparatively small and slender 
elongated teeth, with stouter conical teeth in front and on the 
premaxilla; supramaxilla much more than half as long as maxilla ; 
dentary bone with few widely spaced, large, stout teeth; splenial 
teeth small; operculum almost as broad as deep. Dorsal fin as 
deep as long, with about 16 rays, arising in advance of the middle 
point of the back; origin of pelvic fins exactly opposite to that of 
the dorsal, and the relatively small anal fin, with about 9 rays, 
arising at the posterior termination of the latter. Scales richly 
ornamented in the abdominal region, smooth on the caudal pedicle; 
a few anterior flank-scales slightly deeper than broad. 
Form. Loc. Lower Lias : Dorsetshire. 
All the following specimens were obtained from the neighbour¬ 
hood of Lyme Regis :— 
P. 465 . Type specimen described and figured by Agassiz, loc. cit. 
The small teeth in front of the mandible noted in the 
original description are evidently those of the splenial bone, 
and other specimens prove that the enlargement of the 
teeth does not take place in the middle of that bone, but 
at its anterior extremity. In the crushed ventral region 
there are remains of the squamation of a small fish, 
apparently swallowed. Egerton Coll. 
u 2 
