Biological Survey — Erie-Niagara Watershed 



83 



opaque from preservation but c. 20 rather large oil globules 

 apparent, deep amber in color on the yellowish yolk. In a later 

 stage with the embryo reaching more than once and a half around 

 yolk and apparently ready to hatch, top of head heavily pigmented 

 and dorsal and ventral brown stripes, characteristic of the newly 

 hatched larva, prominent. Yolk sac still deep yellow, its anterior 

 part filled with a large oil globule, and dark thickly distributed 

 chromatophores making their appearance on the underside posteri- 

 orly. ___ Eyes dark, and center of head behind eyes covered by a 

 diamond-shaped patch of small chromatophores. Chromatophores 

 continuing, small and stellate, to form the double dorsal series to 

 end of body, with a similar ventral series behind the vent. 

 Myomeres faintly discernible. 



• 8.5 — 9.8 nun. stage. Newly hatched. Much like following stage 

 figured but yolk sac larger and body proportionately more slender. 

 Pigment identical. 



Fig. 7. — Leucichthys artedi, 10.25 millimeters 



10 J5 mm. stage. Fig. 7. Age about 2 days. Total length 10.25 

 mm; length to vent 6.8 mm; greatest depth behind yolk sac 

 0.85 mm; diameter of eye 0.9 mm; myomeres, 38 to vent, 19 behind. 

 Embryonic marginal fin complete, starting over seventeenth 

 myomere, rising, then notching over twenty-ninth myomere, ris- 

 ing again and notching at peduncle ; ventrally starting beneath 

 yolk sac, breaking completely at vent, and notching at peduncle ; 

 caudal lophocercal ; pectorals large, rounded. Head very blunt, 

 its highest point over posterior part of eye; mouth subinferior, 

 jaws equal. Opaque white in color, differing from Coregonus clii- 

 peaforniis in the restriction of yellow color to the yolk, whereas in 

 the latter this color is diffused in subsurface streaks about the 

 head, above stomach, and in some specimens over the whole body. 

 In the specimen figured, 2 round areas of chromatophores on head 

 followed by a double series of 18 along dorsal aspect to a point 

 opposite vent, thence 24 to tip of tail. These two lines not even, 

 being sometimes alternate and differing in size and number, thus 

 distinguishing the species from Coregonus clupeaformis in which 

 the dorsal series usually perfectly symmetrical. Lateral and ven- 

 tral aspects of head colorless ; 1 very large stellate spot over peri- 

 cardiac region at the beginning of yolk sac; behind this, 2 more 

 or less definite lines extending across sac, and a few chromato- 

 phores arranged longitudinally on underside of sac, very linear in 

 shape. Starting just before end of yolk sac, series of c. 20 large 



