Prof. Agassiz on Viviparous Fishes from California. 387 
1, E'mbiotoca Jacksoni, Agass. 
The body is quite high, of an oval form, greatly compressed 
and similarly arched above and below. The superior arch extends 
to the posterior base of the dorsal fin, whence it continues in a hori- 
zontal line to the base of the tail. The ventral arch of the body is 
similar to that of the dorsal outline. The profile from the dorsal 
nto the end of the snout, is rather precipitate and regularly 
arched, except obliquely above and in front of the eyes, where it is 
slightly concave. The greatest height of the body, including the 
dorsal fin, is equal to the distance from the end of the snout to 
the extremity of the pectoral. The greatest thickness of the body 
is equal to one-fourth its height. The head is of moderate size, 
its length, measuring to the posterior angle of the opercle, being 
about one-fourth that of the entire fish. he mouth is quite small, 
the hind extremities of the intermaxillaries and maxillaries ex- 
tending not farther back than the line of the anterior border of the 
orbit. Buta small portion of the superior maxillary is exposed at 
the angle of the mouth. The anterior edge of that part of the 
snout into which the intermaxillaries fit, is on a horizontal line 
drawn immediately below the orbits. The upper jaw is slightly 
more prominent than the lower, the teeth of the latter fitting wethin 
those of the former. In the upper jaw there are fourteen or fifteen 
teeth; in the lower there are two or three less. They all are 
slightly swollen near the top, and are not pointed but rather blunt- 
ly edged. They do not extend to the angles of the mouth, but 
leave a space without teeth on each jaw. The teeth of the upper 
jaw are but little larger than those of the lower. The teeth of the 
pharyngeals are much shorter than those of the jaws, and form two 
quite moveable plates above, and a triangular one below. ‘There 
are not more than thirty teeth on each of the superior plates, and 
mostly truncated at the top. The four or five teeth, which form 
the inner row of each plate, are more prominent than the others, 
and somewhat pointed. The teeth of the inferior pharyngeal 
plate are similar to those of the upper, but the teeth of its posterior 
range are the most prominent, aud pointed. The lips are rather 
fleshy, and entirely conceal the teeth. Beneath the lower lip 
there is an elongated pit on each side, extending towards the cor- 
ners of the mouth; it is covered by a thin border of the lip. The 
distance from the end of the snout to the anterior border of the 
orbit, is greater than the diameter of the latter by one-third. The 
inferior margin of the orbit is on the middle longitudinal line of 
the body ; and its posterior border is half way between the en 
of the snout, and the posterior angle of the opercle. ‘The oper- 
cular pieces are large. On the preopercle are four concentric rows 
of scales; the two inner and anterior are the longer. ‘There are 
thirteen large scales in the row nearest the eye, and the number is 
