582 
BULLETIN OF THE BUREAU OF FISHERIES 
dark dots, and circulation is established, although the blood flows slowly. The heart 
is situated under the anterior tip of the head. A large artery courses through the 
ventral part of the embryo. It recurves rather sharply in the caudal portion where it 
leaves the embryo. This vessel then divides and several branches course over the 
yolk, reuniting just before reaching the heart. No return circulation is established 
in the embryo. Large dark blotches with irregular outlines, sometimes merely 
Figure 79. — Hypsoblennius hentz. From egg in an advanced 
cleavage stage; probably about 8 hours after fertilization. 
(Drawn by Nell Henry.) 
Figure 81.— Hypsoblennius hentz. From egg with an early 
embryo; tail underneath the opaque yolk; about 2 days 
after fertilization. (Drawn by Nell Henry.) 
Figure 80. — Hypsoblennius hentz. From egg showing blasto- 
derm growing around egg; about 1 day after fertilization. 
(Drawn by Nell Henry.) 
Figure 82. — Hypsoblennius hentz. From egg with well- 
formed embryo, showing blood vessels. Arrows indicate 
direction of flow of blood. About 3 days after fertilization. 
(Drawn by Nell Henry.) 
branching blotches resembling crows feet, are now present on the surface of the yolk 
(fig. 82). 
In about 6 days the embryo encircles the egg, the tip of the tail reac hing to or past 
the head. The eyes are very large and black with a greenish sheen. Heart action 
is very brisk, the beats following each other so rapidly that it is difficult to enumerate 
them accurately. The number of beats probably is close to 200 per minute. A return 
circulation is now established in the embryo. Large vessels still course over the yolk 
