366 



of the development rate, etc., In the normals and hybrids are included in 

 Table 6. 



Table 6. 



Time. 



Gastekosteus X Gastebosteus. 



GaSTEEOSTEUS X FUNDULDS. 



1.05 p. M. 



June 4. 



Fertilization. 



Fertilization. 



4.00 p. M. 



June 4. 



Two cells. 



Two cells. 



4.ao p. M. 



June 4. 



In 4 cells. 



In 4 cells. 



4.45 p. M. 



June 4. 



In 4 cells. 



In 4 cells. 



4.55 p. M. 



June 4. 



Begun on 8 cells. 



Begun on 8 cells. 



5.15 p. M. 



June 4. 



Close of 8 cells. 



Close of 8 cells. 



5.25 p. M. 



June 4. 



Begin. 16 cells. 



Begin. 16 cells. 



6.05 p. M. 



June 4. 



In 32 cells. 



In 32 cells. 



9.15 a.m. 



June 5. 



Late segmentation. Disk begin. 



Late segmentation. Disk less 







to spread. ', 



spread than in normals. 



11.40 a.m. 



June 5. 



Germ ring well formed. 



No indication of germ ring. 



2.00 P. M. 



June 5. 



Germ ring and embryonic shield. 



No indication of germ ring. 



7.00 P. M. 



, June 5. 



§ over yolk. 



Germ ring and shield well de- 

 veloped. 



6.30 A. M. 



July 6. 



Blastopore closed. Embryo 

 formed. 



5 to f over yolk. 



8.00 A. M. 



June 7. 



Embryo developed with eyes, 



i over to closure of blast. Embryo 







brain, etc. 



short and completely formed. 



Fuudulus heterocUtus, female, 



X 



Stenostomus chrysops, male. 



In this cross there is always a fairly large proportion of the eggs 

 fertilized. The per cents in four experiments were as follows: 



Experiments 103b 70 per cent. 



106 40 " " 



122 30 " " 



508 58 " " 



There is usually a considerable proportion di- and poly-spermic. This 

 amounted to 18 per cent, and 20 per cent, in two experiments in which the 

 count was made. The eggs would develop to the closure of the blastopore 

 with the embryo too short though considerably better formed than in the 

 cross Fundulus heteroclitus and Tautogolabrus adspersus. The embryo in 

 some cases may be two-thirds normal length, with the blastopore remaining 

 a rather large oval or slit. Quite a variety of conditions in blastopore 

 closure obtain here, but do not merit detailed description. The relative rat^ 

 of development for the normals and hybrids is detailed in Table 7. 



