24 ARKIV FÖR ZOOLOGI. BAND 10. NIO 8. 



GU t in my account of the fin-muscles.^ As regards the fin 

 rays, Bridge writes: »Each fin ray is cleft basally and 

 the two arms, which terminate inferiorly in thin, plate-like 

 expansions, and not in articular surfaces, closely and firmly 

 clip a distal radial segment.» 



Triacaiitliidae. 



The anterior dorsal fin inserts less cranially than in 



Balistes. The first spine of this fin is enlarged but not 



modified (Hollard). Nothing is known about the radial 

 elements. 



Tetrodoutidae. 



Brigde writes: »The cartilaginous distal extremities of 

 the (proximal) segments fuse together into a continuous pe- 

 ripheral margin, which is separated from, but at the same 

 time loosely connected with, the distal segments by an inter- 

 vening träet of fibrous ti8sue.> The distal segments are carti- 

 laginous nodules connected by fibrous tissue. I can confirm 

 this statement, but I have found that the tissue between the 

 proximal and distal segments in young specimens consists of 

 fibrous pro-cartilage, which without doubt, develops into 

 fibrous cartilage in adult specimens. 



Diodoiitidae. 



The structure of the radial elements shows the same 

 principal characters as that of the Tetrodontids, but the di- 

 stal segments are elongated cartilaginous rods. 



Molidae. 



My studies have confirmed Bridge's statement. I refer 

 to my paper on the body-muscles, in which descriptions and 

 figures of the radial elements and the fin-muscles have been 



* Studies on the Plectognaths, 4. The Body-muscles. — Arkiv f. Zoologi. 

 Bd. 8 (1913). 



