206 THE ZOOLOGIST 
and with a knob-like papilla at its extremity. In the direction 
of their length these gill-rakers have an §-like curve. They form 
a very close filter. The lining of the top of the gullet is a thick 
mucous membrane, covered with papille in the centre, and at 
the sides has longitudinal corrugations, where it is pressed down 
on to the gill-slits between the arches. The pharyngeal teeth 
are in three rows, 5-8-2 and 2-3-5, slightly hooked at the ends. 
There is no callous pad, the teeth biting against the thick mem- 
brane mentioned above. 
Levciscus cepHatus. The Chub.. Fig. IL, 1. 
Has seven small horny gill-rakers on the first cerato-hypo- 
branchial, with one on the epibranchial. The other arches are 
furnished with similar gill-rakers, but placed rather far apart 
and interlocking. They do not form such a good filter as in the 
fishes already described. The pharyngeal teeth (Fig. II., 1) are 
in two rows, mostly uncinate (i.e. hooked) at the point, and 
bite against a horny pad that fits against a portion of the basi- 
occiput shaped to receive it. The lower pharyngeal bones are 
strong, but lightened by their hollow shape stiffened with cross 
diaphragms. Food is mostly vegetable, but this fish devours 
insects, and can be caught with worm-bait. 
Leuciscus mERYTHROPTHALMUS. The Rudd. Fig. III. 
Has seven very short horny gill-rakers, about one-fourth of the 
depth of the gill lamina belowit. There are three on the epi- 
branchial. The other arches have short stumpy gill-rakers that 
form, however, a close filter. The pharyngeal teeth are in a 
double row, 5-2 and 2-5, with a slight hook at their ends. Ags 
many as eight loose teeth were found, some embedded in the 
tissues round the teeth, and others occupying places where they 
would eventually become solidly attached. A thin, hard pad, 
shaped like the ‘‘ spade”’ in playing-cards, was on the under side 
of the skull for these teeth to bite against. 
Levuciscus rutinus. The Roach. 
The pharyngeal teeth of this fish are in a single row each 
side, and slightly curved at the point; they bite against a horny 
callous pad. 
