320 



FISHES 



remains to guard them. 

 During this time the slen- 

 der cylindrical hind-limbs 

 of the male are enlarged 

 and covered with close- 

 set blood - red filaments 

 two or three inches in 

 length (Fig. 25, B). 

 These structures afford 

 an interesting example of 

 secondary sexual charac- 

 ters in the male which 

 disappear after the breed- 

 ing season. Evidently 

 they have some definite 

 function in relation to the 

 care of the eggs. It has 

 been suggested that they 

 act as accessory gills, en- 

 abling the male to obtain 

 sufficient oxygen without 

 leaving the burrow to in- 

 spire air at the surface. 

 Considering, however, the 

 function performed by the 

 male Protopterus and by 

 other male fishes which 

 guard their eggs, of pro- 

 viding the latter with 

 oxygen during their de- 

 velopment, it would seem 

 more probable that the 

 use of the filaments in 

 Lepidosiren is to provide 

 for the respiration, not of 

 the parent himself, but of 

 the ova. The water in 

 the burrow is probably 

 deficient in oxygen, and 

 the eggs may be able to 



