THE DERMAL FIN-RAYS OF FISHES, 



487 



cylindrical, unjointcd proximal half, and a flatter, irregularly 

 jointed distal half in the fin itself. The proximal ends bear 

 much the same relations to the muscles as do the lepidotrichia. 

 The body-scales extend over the dermal rays to near the edge 

 of the fins. These camptotrichia are deeply embedded. 



aci 



bp 



Fig. 3. — Dia£:rammatic figure of a section ilirougli the dorsal fin of 

 Acipenser. For tlie letterin<^ see p. 517- 



whereas the scales are in the more superficial layers of con- 

 nective tissue (Text-fig. 5). 



Such is the structure of the dermal rays in living fish, and 

 the relations of these rays to the scales, the muscles, and the 

 endo-skeletou are illustrated in figures 1, 2, 3, and 59, and in 

 the text-figures. We now endeavour to trace out their origin 

 and homologies. 



