10 THE PELAGIC STAGES OF YOUNG FISHES. 



Species No. 26. 



Plate II. Figs. 1-3. 



Two eggs only of this species (Motella, or some close]}' allied fish) were 

 obtained during the summer of 1884, and these were taken on July 25. The 

 stages represented in Figs. 1 and 2 resemble somewhat the corresponding 

 stages of Motella argentea, seen in PI. XY1II. figs. 3 and 5 ; but differ from 

 them m having less pigment, a colored globule, and a more granular aspect, 

 which is most strongly developed on the yolk around the head. These 

 eggs measured respectively .75 mm. and .76 mm. ; and the brassy yellow 

 oil-globule in each was .1-1 mm. in diameter. 



In one egg there was no pigment on the yolk, and in the other (Fig. 1), 

 only a single small spot near the embryo. In the younger stage (Fig. 1) 

 the embryo is already remarkably granular, the granules being larger on 

 the yolk at either side of the head than elsewhere. In the stao-e of Fig:. 2, 

 just before hatching, the granulation is somewhat stronger, and the inner 

 and posterior part of the eyes is marked with black dots. The pectorals 

 are well advanced, and there is a manifest concentration of pigment in 

 definite regions, which foreshadows the condition reached a few hours after 

 hatching. In the stage of Fig. 3, twelve to eighteen hours old, the pigment 

 is arranged almost precisely as in the }"oung Motella (PI. XVIII. fig. 6), 

 but is much less richly developed. The eye is blue-black, with a reflection 

 of yellow. The lateral line organs agree both in position and number with 

 those of the allied, but plainly different, species figured in Plate XII. In 

 size, general shape, position of the vent, and dimensions, this species agrees 

 closely with the two species above referred to. 



Hemitripterus americanus, C. & V. (H. aeadianus, Storer.) 



Plates II. and III. Figs. 4-18. 



The eggs here described and referred to Hemitripterus are characterized 

 by a rich development of pigment, which makes its appearance some time 

 before the closure of the blastopore. The egg is comparatively large 

 ( 1.U2 to 1.10 mm.), and has a single oil-globule (.15 to .16 mm.), by which 

 it is easily distinguished from the Cottus egg, with which it agrees in re- 



s] t to the early and copious development of pigment. By the time the 



tail becomes well rounded (Fig. 4) we find the embryo thickly pigmented 



