LARVAE, ETC., OP OPHIOCEPHALUS STRIATUS. 
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Fig. 4.—The same seen from above ; op, eye ; au, auditory sac ; 
my, myotonies ; n, notochord ; t, free end of tail. 
Fig. 5.—Egg five hours later, from above. The shaded portion 
of the tail ( t ) shows it bent down, the dotted portion shows it in 
extension, h , heart; sp, body-cavity (splanchnocoel) ; v, yolk ; 
other letters as before. 
Fig. 6.—Newly hatched larva ; length 35 mm. ; eyes colourless. 
pc, posterior cardinal vein joining the caudal vein to form 
the subintestinal vein ; ao, aorta ; au, auditory sac containing 
two otoliths. 
Fig. 7.—Second day larva. Sketch of the capillary network at 
the confluence of the caudal, posterior cardinal, and subintestinal 
veins. The arrows above the aorta indicate the direction of the 
flow of blood in the segmental parietal vessels, ao, aorta \ cv, 
caudal vein; pc, posterior cardinal vein; int, intestine ; ys, 
posterior surface of yolk-sac ; si, subintestinal vein running round 
the yolk. 
Fig. 8.—Third day larva ; length 5*5 mm. ; seen from below. 
pf, pectoral fin ; as, dorsal air bladder seen in optical section. 
Fig. 9.—Pectoral fin of third day larva. It is attached to the 
body dorso-ventrally ; diameter 0 42 mm. 
Fig. 10.—Pectoral fin of seventh day larva, showing primary 
striations ; no fin rays; striated basal muscles ; diameter nearly 
1 mm. 
Fig. 11.—Twelfth day larva. View of the tail end from the left 
side, showing notochord bending up and a capillary formation below 
it, the finely radiate structure of the embryonic fin, and its truncate 
extremity; nc, medullary tube; nch, notochord; cv, caudal vascular 
system, diagrammatic, without distinction of artery and vein. 
Fig. 12.—Twenty-fifth day larva. Tail end from the left side. 
The total length of the larva was 7*5 mm. The figure illustrates the 
commencing fasciculation of the caudal striations, and the basal 
cartilages below the sub terminal convexity of the notochord, df, 
dorsal embryonic fin ; m, muscle fibres below the notochord ; vf, 
ventral embryonic fin, more highly pigmented than the dorsal. 
Fig. 13.—Twenty-eighth day larva ; length 8*5 mm. End of tail 
from the right side ; shows basal prongs and joints of caudal rays 
and the caudal capillaries. 
Fig. 14.—Thirty-seventh day larva ; length 10 mm. Posterior- 
end of the body to show the commencing constriction of the caudal 
fin and the primordia of the dorsal and anal rays, the latter accom¬ 
panied by dense pigment. 
Fig. 15.—Fortieth day ; length 10‘75 mm. Constriction of 
caudal fin progressing. 
Fig. 16.-—Hinder end of another larva of the fortieth day ; length 
12*5 mm. Constriction of caudal fin complete. 
