368 
Fundulus heteroclitus, female. 
x 
Pundulus digp.anus, male. 
Fundulus diaphanus was obtained from a fresh water lake, and was 
crossed many times in both directions with Fundulus heteroclitus. In the 
present cross I was never able to get a higher degree of impregnation than _ 
80 per cent. Often I failed altogether and usually there was only an occa- 
sional fertilized egg—less than 1 per cent. This may have been due partly 
to the difficulty of getting enough good milt. In one instance I found about 
one-half of the eggs polyspermic. The eggs develop along in a normal 
fashion, going somewhat slower in the later stages, and hatch. I have 
reared some of the embryos for two weeks and they seemed perfectly 
active and otherwise normal. The eggs were reared in both fresh and sea 
water. 
Fundulus diaphanus, female, 
x 
Fundulus heic: cclitus, male. 
When Fundulus diaphanus is used as the female nearly all of the eggs 
may be impregnated. Thus: 
EPOTIENe, (GD. i/v.aulehestteae ts vn > Nearly 100 per cent. 
xs Ln ace cy erent . Gane: aes 
“ AGH ses sire riite era rea ie Ge ee 
The eggs are practically all normally fertilized and hatched. These L 
have reared for twenty-two days after hatching. 
Fundulus heteroclitus, female, 
x 
Cynoscion regalis, male, 
The eggs of Fundulus are fertilized as perfectly with the sperm of the 
Squetegue as with its own milt. ‘Thus: 
Bisperiment BiG bo caksees ox Se andsene eee. ...92 per cent. 
“ 15 See oe : Ss ; Ro ata 
Only about 2 per cent. of the eggs are polyspermic. A tabulated outline 
of the development compared with the normal is as follows: 
