Oral Gestation in the Gaff-Topsail Catfish, Felichthys Felis. 37 



Before leaving this subject brief reference may be made to the 

 large size and to the number of eggs which are carried by other silu- 

 roids practicing oral gestation. Evermann and Goldsborough (1902) 

 noted that 39 eggs were taken from the mouth of a 13.5-inch male 

 Conorhynchus nelsoni. The average size of the eggs measured was ten- 

 sixteenths by eleven-sixteenths of an inch. Von Ihering (1888) found 

 eggs of 18 mm. diameter to the number of 3 or 4 dozen in the mouths of 

 "large" males of Arius commersonii {Netuma or T achy sums harbus), a 

 salt-water catfish of southern Brazil. Day (1873) obtained 15 to 20 

 eggs, 0.5 to 0.6 inch in diameter from the mouths of Osteogeniosus mili- 

 taris and various species of the genus Arius in India. Boake (1866) 

 reported the eggs of his Cingalese Arius to be about the size of small 

 grapes. Giinther (1864) says that the eggs of Arius fissus of Cayenne 

 are rather larger than peas. Last of all, but not least, are the eggs of 

 that catfish of Guiana whose native name is jarra-hakka, which are 

 declared by Wyman to measure 0.75 inch in diameter. However, 

 it may be remarked that, although much work has been done in recent 

 years on oral gestation in the catfishes of Guiana, none with eggs so 

 large has ever been taken. 



SIZE OF YOUNG AND NUMBER CARRIED. 



It is to be regretted that no such full data can be given for larvse 

 as for eggs carried by the gaff-topsail paterfamilias. Unfortunately 

 but few lots of larvse were taken, and these larvae were rarely killed 

 at the time of capture, but were kept that their behavior might be 

 studied, their organogeny worked out, and drawings of them made. 



On July 18, 1907, an 18-inch male was caught and from his mouth 

 were taken 21 larvae. One of these, of average size, after being in 10 

 per cent formalin for 24 hours, measured: extreme length (point of 

 snout to tip of upper lobe of caudal) 57 mm. ; outside width over eyes 

 11.25 mm.; length of dorsal spine 14.75 mm.; yolk-slit, longitudinal 

 measurement 18 mm., transverse 16.5 mm. 



On July 7, 1908, an ovigerous male was taken in whose mouth were 

 found 6 larv^ae measuring 53 to 55 mm. long over all. On July 21, 

 1910, 5 larvae were taken from the mouth of a male, but unfortunately 

 neither father nor young was measured. Young of about this stage 

 are shown in figure 11, plate iv. 



As to the size the young attain before leaving the shelter of the 

 paternal mouth, fairly definite data can be given. In general it may 

 be stated that departure does not occur until the fishlet is grown, 

 i. e., until the yolk-sac has been inclosed by the body- walls. This a 

 'priori conclusion was verified when, on July 20, 1908, my fishermen 

 brought in a young catfish which they had taken from the mouth of 

 an adult some hours before. In this fish, which was about 4 inches 

 long, the body-walls had completely closed over the yolk of which 



