52 THE PELAGIC STAGES OF YOUNG FISHES. 



Tig. 11. A somewhat older fish, showing a more advanced stage of the dorsal thickenings. The embryonic 



fold much reduced. 

 Tig. 12. A similar stag.', in which the dorsal thickenings arc not yet distinctly marked. 



PLATES IV. and V. 



Temnodon saltator, Lin. (Pomatomus saltatrix, Gill.) 



Profile view of the early ring stage, treated with osmic acid and chrome-platinum solution. X 55. 



Same, seen from above. X 55. 



Just after closing of the blastopore, showing the peripheral arrangement of the yolk-segments. X55. 



A somewhat older stage, seen from the ventral side. 



A section of the yolk-sae at the stage of Fig 3, showing the two strata of the ectoderm (ec), the 



thin periblast ( p) aud the yolk-segments (ys). 

 Stage shortly before hatching. 



.lust hatched. Yolk-segments arc still quite distinctly seen. 



Thirty-six hours old. Yellow pigment has reached its maximum point of development. 

 Sixty hours old. 

 Eighty hours old. 

 Nine days old. 

 A later stage, showing the muscular thickenings for the posterior dorsal and the anal, and the 



bilobed heteroeereal stage of the tail. 

 A stage still farther advanced in the development of the unpaired fins. 



Permanent rays appear in the dorsal aud anal. The permanent caudal appears like a second anal. 

 Young fish measuring 9 mm. in length. The embryonic lobe has disappeared, aud the caudal has 



assumed the homocercal form. 



PLATE VI. 

 Lophius piscatorius, Lin. 



Fig. 1. The egg magnified 25 diameters. 



Fig. 2. Three eggs enclosed in saccular spaces of the mucous band. 



Fig. 3. Showing natural size of the eggs. 



Figs. 4-7- Different views of the unhatched embryo. 



Fig. S. Portion of the embryo and the yolk-sac, showing the character of the pigment. 



Fig. 9. Frontal view of the embryo. 



Fig. 10. One of the chromatophores of the yolk-sac enlarged. 



PLATES VII. -IX. 



Ctenolabrus adspersus, Walb. (C. coeruleus, Stoker.,) 



Figs. 1-34. X about 50. 



Fig. 1. The freshly laid egg, before fecundation. Quite opaque from the presence of numerous highly 

 refractive granules in the peripheral layer of the yolk. 

 Profile view of the fecundated egg, showing the blastodisc. 

 Same, seen from above. 

 The two-cell stage from above 

 Four-cell stage in profile. 

 Eight-cell stage in profile. 

 Same, from above. 

 Sixteen-cell stage, seen from above. 



In the same stage as Fig. 8 after the disappearance of the nuclei. 

 The eiglil cell stage in process of dividing. 



