20 ERNEST WARREN. 



not possible to say that the hybrid as a whole is closer to one 

 parent than to the other. 



In the case of hybrid moths, the cross Smerinthus 

 ocellatus ^ x Sm. populi ? [Westwood] is nearer to 

 the male-parent ocellatus, and the cross Sm. populi (^ x 

 Sra. ocellatus ? [Standfuss] is also nearer to the male- 

 parent Avhich is populi. 



Similarly in the case of mammals, the cross Equus 

 burchelli cJ x E. caballus ? [Ewart] is nearer to the 

 zebra in the amount of striping, while the cross E. caballus 

 cJ X E. burchelli ? [Ewart] is closer to the horse in the 

 comparative absence of stripes in the hybrid. 



Also, the mule is perhaps somewhat closer in general 

 character to the male-ass than to the female-horse, and the 

 hinny is stated to be nearer the male-horse than to the female- 

 ass. 



In these several examples the male appears to be pre- 

 potent. 



Nevertheless, no general rule exists, for among fishes the 

 cross Acerina cernua (J x Perca fluviatilis ? [Kam- 

 merer] is strikingly close to A. cernua, while the cross 

 Perca fluviatilis (^ x A, cernua ? [Kammerer] is also 

 very near to cernua. 



In the cross of the moths Saturnia pavonivee cJ x 

 S. pyvi ? [Standfuss] the hybrid is obviously nearer to 

 pyri, the female-parent. 



In the case of recipi'ocal crosses of the moths Deilephila 

 euphorbias c^ x D. vespertilio ? [Berge-Rebel] and of 

 D. vespertilio (^ and D. euphorbiee ? [Berge-Rebel], 

 the hybrids appear to be as nearly as possible intermediate 

 between the parent species, and there is very little difference 

 between them. 



In the above few examples of the crossing of distinct 

 animal species the resulting hybrids exhibit considerable 

 diversity with respect to their genei'al average character 

 compared with that of the two parent-forms. 



We see that (1) the hybrids may be nearer to the male- 



