138 
FISHES OF THE CHALK. 
genera Salmo and Clupea, but does not conform 
to the characters of either ; it may, however, be 
convenient to affix some name as a temporary dis- 
tinction, and, for reasons hereafter mentioned, the 
following has been chosen. 
Salmo ? Lewesiensis. 
The body of this ichthyolite is of an elongated 
oval form, and covered with smooth, delicate/ 
semicircular scales. The trunk is subcylindrical, 
the back slightly ridged, and the abdomen rounded. 
The head, so far as can be ascertained from the 
specimens in my collection, appears to have been 
of an obtuse form. The eyes are placed high on 
the head ; the mouth and jaws resemble those of 
the Salmo odoe, but no vestiges of teeth are per- 
ceptible ; the lips are rounded as in the Perch 
(Vevcdi Jluviatilis'). The opercula hranchialia con- 
sist of three or four plates, and in one example 
ten or eleven of the branchiostegous rays remain. 
The pectoral fins lie close to the gill-covers, and 
are composed of seven or more rays. The ventral 
fins are attached to the abdomen, and each has six 
or seven rays. The caudal fin is unknown ; but 
the small adipose fin or process, so constantly ob- 
servable between the dorsal fin and tail, in the 
recent fishes of the salmon tribe, is distinctly 
shown in one specimen. 
The ventral fins being situated behind the pec- 
toral, places this fossil fisli in the order abdominales ; 
while the relative situation of these parts, the 
adipose dorsal appendage, the structure of tlie 
opercula, and the rounded form of the abdomen, 
point out some affinity to the salmo. The absence 
