PAIRING, COURTSHIP, AND PARENTAL CARE 297 



there are external movable bony appendages which may serve 

 to grasp the female during intercourse. As in the case of the 

 intromittent organ of the Four-eyed-fish, the priapium is placed 

 either to the right or to the left, but is never symmetrical in 

 position. 



The breeding habits of the Cyprinodonts are of great interest, 

 and the small size and pretty appearance of the fishes, and the 

 elaborate courtship in which many of them indulge, makes 

 them great favourites with aquarium lovers of all countries, 

 particularly as they will breed fairly freely in captivity. In the 

 species in which they are brilliantly ornamented, the males will 

 dart about with rapidity, displaying their manifold charms, 

 and exhibiting a good deal of excitement. In some forms the 

 females seem to encourage the advances of the males, but in 

 others they may be very shy and their mates have to exercise 

 great perseverance and not a little cunning in approaching 

 them. It is of some interest to note that in those species in which 

 the attentions of the male are encouraged by the female the 

 intromittent organ is quite short, but where she endeavours, as 

 it were, to make him keep his distance, it is much longer. 

 Owing to the rapidity with which it usually takes place, the 

 actual transference of the milt from the male to the female 

 has rarely been observed in detail, but Dr. Philippi has described 

 the process as it occurred in two species of Glaridichthys kept in 

 his aquarium. He observed that during coition the male bent 

 his anal fin round either to the right or to the left, so that its 

 tip pointed forward and somewhat upward, and then darted 

 towards his mate, touching her genital aperture with the 

 processes at the extremity of the fin. The contact only took 

 place for a moment or two, and the impetus of the rush on the 

 part of the male carried him past the female. So rapid was the 

 whole proceeding that it was impossible to see the spermatozoa 

 actually transferred, but by taking a male fish and laying it 

 on a glass slide Dr. Philippi found that by slight pressure on 

 its body small lumps of milt were extruded which adhered to 

 anything with which they came into contact. Examination of 

 one of these lumps under a microscope showed that it was 

 composed of spermatozoa surrounded by a sticky fluid, and the 

 reproductive organs were found to be full of similar lumps. 

 The formation of these masses or spermatophores is clearly 

 designed to prevent the dispersal of the spermatozoa in the 

 water, and when the intromittent organ is brought into contact 

 with the body of the female as described above, some of these must 



