EMBRYOLOGY AND LARVAL DEVELOPMENT OF TELEOSTEAN FISHES. II7 



Eggs. — The eggs are highly transparent and ellipsoidal in form, having a major 

 axis of 1. 1 5 to 1.25 mm. and a minor axis of 0.55 to 0.80 mm. The yolk is broken 

 up by refraction planes, giving it the appearance of being made up of large cells. The 

 eggs of this species resemble those of Anchovia brownii more closely than those of 

 Anchovia mitchilli.'^ 



Embryology. — The embryological development of these eggs differs from that of 

 the pelagic eggs here described only in a few unimportant details. The protoplasm 

 becomes concentrated to form the blastodisc at one pole of the major axis. As the 

 blastoderm grows round the yolk, its posterior pole does not remain at a relatively 

 fixed point, as is the case in many spherical teleostean eggs, but recedes as the anterior 

 pole advances. The center of the blastoderm, therefore, remains at one pole of the 

 major axis. (Figs. 69 and 70.) The blastopore finally closes at the opposite pole. 





Fig. 69.— Egg showing an early stage in differen- 

 tiation of embryonic axis. 



Fig. 70. — Egg showing a late stage in differentiation 

 of embryonic axis. 



ANCHOVIA ARGYROPHANA. 



When the embryo is fully differentiated, it lies approximately parallel with the major 

 axis of the egg, the head being strongly deflected at the end of the yolk mass. (Fig. 

 71 and 72.) 



Larval development. — The newly hatched larvae are approximately 3 mm. in length. 

 The yolk sac remains relatively large and tapers to a point at the posterior end. The 

 body is relatively slender, and the vent is located less than one-fourth the length of 

 the body from the posterior end. Black chromatophores occur in a series along the 

 intestine posterior to the yolk sac and at the base of the ventral-fin fold posterior to 

 the vent. Figure 73 illustrates a larval fish approximately eight hours after hatching. 



One day after hatching (fig. 74) the larvae have grown to a length of approximately 

 3.4 mm. The yolk is largely absorbed. The distribution of pigment remains essen- 

 tially as in the newly hatched larvas, but the chromatophores have increased mate- 

 rially in size. 



fl Kuntz, A.: The embri'ology and larval development of BairdieUa chrysura and Anchmiia mitchiUi. Bulletin Bureau of 

 Fisheries, vol. xxxiu, 1913, p. 14. 



