16 THE PELAGIC STAGES OF YOUNG FISHES. 



whole dorsal line of the body is marked by a dense line of black pigment. 

 In Fig. 12 a small patch of bine is seen below the pectoral, and this becomes 

 much larger in subsequent stages. In passing from Fig. 11 to Fio-. 15, we 

 have a very complete series, exhibiting all the principal transitional phases 

 of the tail, from the leptocardial (== pratocercal, Wyrnan, lopkoeercal, Ryder) 

 to the homocercal condition. The serial homology of the permanent caudal 

 with the anal is well shown in Fig. 14. The obvious functional importance 

 of the caudal has both strengthened and accelerated its development, and 

 at the same time may contribute to bring about the upward curvature of 

 the caudal axis, as maintained by Ryder.* 



Fig. 15 represents a small Blue-fish, measuring 9 mm. in length. The 

 tail fin is but slightly forked ; the anterior dorsal is rudimentary, but the 

 base of the permanent fin-rays is already present ; permanent fin-rays are 

 present in the posterior dorsal, as well as the anal ; the pectorals are large, 

 and the ventrals rudimentary. The teeth of the upper and lower jaws are 

 already quite prominent. The eye is bright blue, and the body bluish silvery 

 with a few faint pigment-cells uniformly scattered over the flanks. The 

 Carangidai with rudimentary ventrals and no anterior dorsals are evidently 

 genera representing the embryonic stages of this family. 



Already when quite young the Blue-fish shows its ferocious habits. 

 Small fishes of the size of those figured in Plate V. (Fig. 12) attack other 

 young fishes if kept in the same glass dishes. By the time the little Blue- 

 fish have reached the size of Figs. 14 and 15 in Plate V., they are fully 

 as dangerous to other fishes as are the merciless adults while in pursuit of 

 their food. A couple of young of these dimensions will attack much larger 

 Flounders, Motella?, Cunners, or Smelts, and soon devour every living thing 

 kept in confinement with them for any length of time. 



Lophius piscatorius, Lin. 



Plate VT. Figs. 1-10. 



The eggs of Lophius have been obtained early in June and late in Au- 

 gust. They are laid in an immense mucous band, from two to three feet 

 broad and from twenty-five to thirty feet or more long. Occasionally a 

 single rir^ j s found floating at the surface. The mucous mass is of a light 



* John A. Ryder. " ^.n Outline of the Development of the Unpaired Kins of Fishes," American Nat- 

 uralist, 1885, p, 94. 



