40 Papers from the Department of Marine Biology. 



Holder (1904). however, speaks of the fish with eggs in their mouths 

 biting ravenously at hooks baited with shrimp. But Evermann 

 and Goldsborough (1902) expressed the opinion that Conorhynchus 

 nelsoni does not feed during gestation. Day (1873) found no trace 

 of food in the intestinal tracts of either Arius or Osteogeniosus, both 

 oral gestators of India. Boake (1866) concludes that the Ceylonese 

 Arius may feed on microscopic "nutritious particles" floating in the 

 water, but Turner (1867), after studying Boake's specimens, thinks 

 that the amount of food obtained in this way would be practically 

 nil. On the other hand, Wyman, though inclined to think that 

 gestating males fasted, from finding in the mouth eggs of another 

 species was led to believe that the fish might have disgorged the eggs 

 in order to feed, and that on taking them up again the eggs of "another 

 species" were also included. The wording of his sentence indicates 

 that the other species was also a catfish. If this be true it may be 

 conjectured that these eggs were the smaller unripe eggs of the female 

 from whose ovary came the other ripe eggs, extruded and taken into 

 the mouth of the male at the same time with the ripe eggs. 



Save Holder (1904), previously referred to, the only other investi- 

 gator, in all the literature of oral gestation known to me, who has 

 found an incubating male to feed, is von Ihering. He (1888) speaks 

 of catching females of Arius commersonii on the hook, but says that 

 males whose mouths are filled with eggs do not take the bait except 

 on rare occasions. Excepting these authors, all writers agree that 

 fishes practicing buccal incubation fast during this period. Such is 

 my conclusion arrived at after 6 years' study and research on the 

 gaff-topsail. In this fish the incubatory period has not been defi- 

 nitely worked out since it has been found impossible to carry early 

 eggs through hatching to the stage of independent life. However, 

 so far as it has been made out by piecing together my observations, 

 incubation continues about 70 days. 



Many authors have noted that the incubating fish at or toward 

 the close of gestation are thin, emaciated, worn out with their labors. 

 Unfortunately I have taken but few gaff-topsails in late incubation, 

 and none towards its close, and have noted no striking emaciation in 

 the fishes captured. A few, however, have been rather thin and hi 

 poor condition, and moreover it has always been noticed that incu- 

 bating males taken in June and July do not seem to have much stamina. 

 After being relieved of then 1 eggs they die very quickly, whereas females 

 and non-breeding males are very active and robust, and as a fisherman 

 once remarked "require a good deal of killing" with a fish club before 

 they become quiet. From this it would seem that the duty of incu- 

 bation bears rather heavily on the male. 



