Nr. 91 



CONTHIB. TO THE LIFE HISTORY OF THE FISHES 



29 



The importance of this will be further discussed under Ihe 

 following stage. 



In a capsule from Gulosen, February 1909, was found an 

 embryo lotal length abt. 50 mm. Heie Ihe loose flap of Ihe 

 pectoral fins has grown out past the Ist gill-slil, reaching almost 

 to the spiraculum. The free llap of the pectoral fin exlends 

 from the 5th gill slit forward in front of the first. Thus, while 

 the junelure, or overgrowing of the gill-slits is taking place, the 

 foremost part of the pectoral fins is free. During the joining 

 process, the gill threads are forced over down lo the ventral 

 side, which can take place as they are in a position lo pass 



Fig. 8. Embryo of R. radiata from Gulosen Vs 1910, total length abt. 

 (i0 mm., dorsal view. 



the free pectoral fin flap. At this stage of developemenl, at 50 

 mm., the gill-slits above the pectoral fins are also closed, bul 

 their position may be observed with slight magnification, and 

 the gill threads, which are fairly long, have come on the ven- 

 tral side (pl. I, fig. 5). The anal fin is still comparatively 

 broad, and in the ventral fins there is a slight incurvation deno- 

 ting the incipient division of the same. The mouth is now 

 shaped as a tranverse slit. Ocular pigment distinct. In front 

 of the mouth is a triangular disc-shaped extension, which later 

 grows together at the lateral edges with the advancing llap of 

 the pectoral fins (pl. I, fig. 5). In an embryo total length abt. 



