Biological Survey — Erie-Niagara Watershed 



in 



diameter of oil globule 0.4 mm; length to end of yolk sac 2.2 mm; 

 myomeres, c. 18 before vent, c. 18 behind (incomplete). Char- 

 acterized by large oil globule occupying anterior part of very large 

 yolk sac; embryonic marginal fin granular in texture originating 

 dorsally at base of brain and ventrally at middle of yolk sac, 

 moderate in height without pronounced elevation; pectorals well 

 developed. Yery dark eye ; sparsely distributed, large light-colored 

 stellate chromatophores on bottom of yolk sac ; usually 1 or more 

 on dorsal and ventral aspects of intestine; uneven series of very 

 small unequal ones ventrally behind vent, with divisions of 

 myomeres (few or all depending on individual) marked by black 

 line running from ventral edge to lateral line. 



Fig. 18. — Perca flavescens, 20.5 millimeters 



Postlarva. 20.5 mm. stage. Fig. 18. D. Ill to VII, II, 9 to 12 

 (very incomplete) ; A. II, 6 to 8 ; C. shallowly forked; V. developed, 

 below P. Total length 20.5 mm; standard length 17.25 mm; 

 length to vent 10.5 mm; length to first dorsal 5.95 mm; length of 

 maxillary 2.0 mm; greatest depth 3.6 mm; diameter of eye 1.5 

 mm ; myomeres c. 18 before vent, 18 behind. Body greatly com- 

 pressed, more elongate than adult yellow perch but decidedly 

 deeper than pike perch of this length; mouth large, with very 

 small sharp teeth discernible but no canines, maxillary reaching 

 to middle of eye ; pelvic fins very close together. Round and stel- 

 late chromatophores on head and double line dorsally to end of 

 body ; scattered also over sides of head and more or less evenly over 

 sides of body; many specimens with dark subsurface area over 

 stomach region; rather indistinct ventral row of large stellate 

 chromatophores to vent and irregular double series from vent to 

 caudal, darkest at base of anal ; dorsals, anal, and caudal speckled ; 

 banded coloration of the adult not evident in these preserved 

 specimens. 



Adult. Specimens of 40 mm. fully developed, definitely banded. 



Stizostedion sp. — Pike-perch 



Record of Capture. — These small pike-perch were hatched at 

 Thurlow hatchery, Ontario, May 7, 1927, but in the absence of 

 other data we cannot determine the species. 



Description.— iV^ei/'/?/ hatched larva. Fig. 19. Total length 

 7.75 mm; length to vent 3.7 mm; greatest depth 1.5 mm; diameter 



