EXPLANATION OF THE PLATES. 



PLATE I. 



Cottus grcenlandicus, C. & V. 



l'h.s. I 5. 



Figs. 1, 2, 3. Three eggs in mail v the same stage of development, sliowing a variable number of oil- 

 globules, and the distribution and color of the pigment. Magnified about 50 diam. 



Fig. 4. Just batched. Possibly a different species, X 55. 



Fig. 5. A few hours after hatching. Has fewer pigment-patches on the embryonic fold than the specimen 

 described by Agassiz (Young Stages, etc., PI. III. Figs. 2, 3) Round fleshy pectorals promi- 

 nent. X 55. 



Species No. 28. 



Figs. 6-8. 



Fig. 6. An egg taken August 15, 1884, measuring only .63 X .65 mm. X 55. 



Fig. 1. Jusf hatched. x 55. 



Fig. 8. Probably a little older, and possibly not belonging lo the same species. Veni lateral. X 55 



PLATES 11 wn III. 



Species No. 26. 



Figs. 1-3. 



Fig. 1. Egg of some species of Motella, found July 2."i, 1884. 

 Fig. 2. A later stau'e, found ai the same time. X 55. 



Fig. 3. Young at time of hatching, showing the position of the lateral-line organs, the lateral nerve, ami 

 three cranial nerves supplying the lateral-line organs of the bead. X 55. 



Hemitripterus americanus, ('. & Y . (H. acadianus, Storek.) 

 Figs. 1-1-'. 



Figs. 1-. 5. T\vo eggs in about the same stage of development, but showing some differences in color. Head 



remarkably wide. 

 Fig 6 A somewhat later stage, afb r the pigment-cells have spread over the whole yolk-sac. 

 I'il . 1 .1 usl before hatching. 

 Fig. 8. Twelve hours alter hatching. Arch of the dorsal fold unusually high. The lime pigment-patches 



on the fold are characteristic of this species. 

 Fig. 0. Thirty-six hours old. 

 i ( 'ig. 10. A much later stage, showing the thickening along the dorsal line, which represents an early stage 



in the development of the dorsal lius Remarkable for its lighi color. 



