130 American Fisheries Society 



as yet the caudal fin is not differentiated. There is a 

 slight thickening on the postero-ventral surface at a point 

 where the first of the fin rays are to appear. The noto- 

 chord is still straight and the eyes are still symmetrical. 

 The pigmentation as shown in the figure is quite different 

 from that at the time of hatching. The patch shown at 

 the angle of the lower jaw is very characteristic, as are 

 the four large pigment spots just ventral to the heart. 

 There is a line of pigment along the dorsal side of the 

 notochord and corresponding lines along the dorsal and 

 ventral borders of the body. The spots along the ventral 

 border are much more expanded than those forming the 

 other lines. The patches on the abdominal region and 

 over the heart are not as constant as the others men- 

 tioned. The dorsal finfold is either unpigmented or has 

 a few scattering spots with no constant arrangement. 

 In the ventral finfold the pigment is conspicuous and 

 fairly regular. Here the spots form two lines that are 

 practically unbroken. All the pigment so far described 

 is black or brown as seen with transmitted light. Mingled 

 with the black pigment of the ventral finfold are a num- 

 ber of small red asters of irregular distribution. 



Between the second and third stages what we may call 

 the more critical changes take place. The external 

 changes are the migration of the eyes, the development 

 of the fin rays, and the differentiation of the caudal fin. 

 Accompanying the differentiation of the caudal fin is the 

 upward bending of the notochord. The migration of the 

 eyes is usually referred to as a very rapid change, con- 

 suming only a few days at the most. While it is only a 

 question of interpretation as to what should be included 

 in that period, I would favor including at least all those 

 stages between the end of the second week and the end 

 of the eighth week. Properly I think it should include 

 the period extending from the time of fertilization to the 

 completion of the metamorphosis. To refer to it as oc- 

 cupying only a few days is entirely misleading if not 

 erroneous. 



