140 FISHES OF SAN DIEGO—EIGENMANN. 
motion of the tail causes the embryo to revolve around its snout as a 
pivot. 
At this time the lateral organs show as four or five hyaline projec- 
tions on either side of the body. On treating the eggs with Perenyi’s 
fluid just before hatching, the contents of these cells become granular. 
The embryo contracts and a slender thread, the nervus laterale, can 
be seen connecting them. Slender roots are also seen extending from 
these cells to the embryo. 
The yolk is rapidly reduced in size and the embryo doubles its length 
in about twenty-four hours. The oldest larva examined is represented 
in Fig. 14, forty-eight hours after hatching. 
Pigment does not appear in these eggs or larve during the time that 
they were examined. 
In the segmented yolk these eggs agree with those of the shad and 
other physoclistie fishes. 
Stolephorus compressus (Girard). 
Girard, Pacific R. R. Survey, X, 336, 1859. 
R. Smith ’80; J. and G. ’80a., 457; id. ’81, 37; id. ’82, 276; R. Smith ’85, July; E. 
and E., 1. c., June, 1889. 
Quite common, but not so abundant as ringens or delicatissimus. 
DEVELOPMENT OF STOLEPHORUS COMPRESSUS. 
(Plate x, Figs. 1-5). 
The eggs of this species can readily be distinguished from other pelagic 
eggs. ‘They are spherical, transparent, without oil globules, and with 
a totally segmental yolk. They measure 0.76 millimeter. A single 
egg of this species was found April 24 and is represented in Fig. 1. 
The next appearance of these eggs was on April 26, when two eggs 
were found, the one represented in Fig. 2 the other in Fig. 4. The 
one represented in Fig. 2 hatched in about sixty hours. The time 
required for hatching was considerably reduced in eggs found later, 
doubtless owing to the rise in temperature. More eggs were found on 
June 2, and from June 15 to 25 they were very abundant. 
On hatching these fishes resemble the other species of Stolephorus, 
and but little difference can be made out between the species during 
the first twenty-eight hours after hatching. Up to this time no sign of 
pigment has appeared. 
SYNODONTIDA. 
Synodus lucioceps (Ayres). 
This species is never very abundant at San Diego and has not been 
recorded from here until the present year. It was first observed by me 
on September 14, 1889, and it was caught with hook and line and with 
seines at an average of about one a day till the 17th of December. 
None were observed after that until February 11, 1890, when a single 
Specimen was taken. It was most abundant during November. 
