SCIiENIDiE OF THE EASTERN UNITED STATES COAST. 
151 
Table 3. — Measurements of eggs and oil globules of two examples of the squeteague, Cynoscion regalis. 
The development of the eggs and larvae of this species has been studied by 
Radcliffe, but his results have not been published. The following account of the 
embryology and larval development (figs. 2 to 10) is taken from his notes. The 
work was done on board the United States Fisheries steamer Fish Hawk in the 
spring of 1916, in the lower part of Chesapeake Bay. 
From the relative numbers of eggs taken in the townets at different hours 
spawning appears to occur chiefly at night, especially in the early evening. 
The eggs are pelagic, transparent, spherical, from 0.74 to 1.10 mm. in diameter, 
•with one to four oil globules within the yolk. The egg membrane is thin and 
horny. The smaller eggs (0.74 to 0.85 mm. in diameter) rarely have more than 
one globule, its diameter being about 0.18 mm., but the larger eggs often contain 
two globules, sometimes three, rarely- four. As development advances these 
coalesce into one. After fertilization a very narrow perivitelline space is apparent 
between the egg membrane and the delicate vitelline membrane investing the 
yolk sphere. Occasionally eggs are encountered with a wide perivitelline space, 
and although such eggs may hatch, the resultant larvae are less hardy and the 
condition is presumably abnormal. The smaller eggs appear to considerably 
outnumber the larger ones. 
Eggs in the later stages of development and newly hatched larvae were rarely 
taken in the townet at the surface of the water, and it would appear that during 
development the specific gravity of the eggs increases sufficiently to cause them 
to sink. This also was normally the case with eggs held in containers on shipboard. 
EMBRYOLOGY. 
The eggs of Cynoscion regalis develop in the manner typical of most teleostean 
eggs. Upon fertilization the protoplasm concentrates at one pole of the yolk sphere, 
forming a thin lenticular mass, the blastodisc. Cleavage is regular, the first two 
(fig. 2) and four blastomeres being symmetrical and nearly equal in size. Figure 
3 illustrates an advanced cleavage stage of the blastoderm in an egg containing two 
oil globules. The differentiation of the germ ring and development of the embry- 
onic shield are typical. The appearance of the egg just before the closing of the 
blastopore (12 to 14 hours after fertilization, at temperatures of from 68 to 70° F.) 
is shown in Figure 4. At this stage the embryo extends nearly halfway round the 
