38 THE PELAGIC STAGES OF YOUNG FISHES. 



any of the young I have collected. In the next stage figured (PI. XII. 

 fig. 3), the young fish has greatly changed ; the head is quite elongate, 

 branchiae are present, the lower jaw projecting beyond the upper one, pec- 

 torals large, eye brilliant emerald-green, the yolk-sac has completely disap- 

 peared, the caudal embryonic fin-rays are very marked ; we can also see the 

 first trace of the separation between the caudal, anal, and dorsal. A prom- 

 inent row of large pigment-cells extends along the base of the anterior anal 

 embryonic fin-fold, with a smaller line extending along the upper side of the 

 intestines, a few small pigment-cells at. the extremity of the notochord, along 

 the base of the posterior anal and of the operculum, with two or thre pig- 

 ment-cells along the dorsal line about half-way from the head to the tail. 



" In the next stage figured, the young Osmerus is considerably older, 

 measuring already 22 mm. in length; the caudal is completely separated 

 from the dorsal and anal, in both of which the permanent fin-rays already 

 exist ; there are rudimentary ventrals present in this stage. The general 

 coloring of the body is a light dirty yellow, with patches of more brilliant 

 yellow along the lateral line and base of the head. There is one line of 

 grayish pigment-spots along the dorsal side of the notochord, a very prom- 

 inent line of large pigment-cells running somewhat below the notochord, 

 extending from the base of the pectorals to the vent, with four or five large 

 pigment-cells along the base of the anal and the ventral line towards the base 

 of the caudal. Small pigment-spots extend along the base of the caudal fin- 

 rays, with three or four larger spots at the base of the caudal fin. The oldest 

 stage I have found (PL XII. fig. 5) was not larger than Fig. 4 (PI. XII.) ; but 

 the caudal, anal, and dorsal were in a more advanced condition, the perma- 

 nent fin-rays better marked, the head less elongate, the body behind the 

 ventrals comparatively broader. The great resemblance of this stage of 

 Osmerus to Scomberesox and Belone in the general arrangement of the 

 median fins and the great elongation of the body is striking. Mr. H. J. Rice 

 has, in the Report of the Commissioner of Fisheries of Maryland for 1877 

 (Plates III., V.), given excellent figures of several young stages of the Smelt. 

 The figures here given complement the stages already known, and with 

 those of Mr. Rice give a fair sketch of the principal changes of the Smelt 

 due to growth. The resemblance of the development of Osmerus to that of 

 the Herring, as given by Sundevall. is very striking. Sundevall figures 

 young fishes, which he calls embryo Herring, from 8 to 38 mm. in length, 

 but he does not state whether they were actually raised from eggs of known 



