Reed and Lloyd. — Spines of Catfishes 203 



two parts, each of which divides into two and so on to 

 the periphery of the fin. Because of this branching the 

 ray becomes fan-shaped, supporting a much greater ex- 

 tent of the web at its free edge than at its base, Fig. 1. 

 Second, each division of the ray is transversely 

 segmented, a state which makes for flexibility as well as 

 indicating its morphologic nature. 



In what may, for convenience, be termed the "higher" 

 or more modified bony fishes — strong and sharp spines 

 may be present in all fins excepting the caudal. The 

 Yellow Perch serves as a good example. The first dorsal 

 of this species is supported entirely by spines. They are 

 heavy at the base and with an even surface regularly 

 taper to a sharp point at the margin of the fin-web, Fig. 

 2. They are without either transverse segments or 

 branches. Spines of this type may be said to result from 

 a suppression of branching and segmentation during 

 development. Each spine, therefore, as an entity is an 

 exact match for a soft ray. When the segmentation per- 

 sists without the branching there results what has been 

 termed a simple ray, Fig. 3. So far as definitive struc- 

 tures are concerned the simple ray occupies an inter- 

 mediate position between soft rays and spines. 



The presence of the catfishes among the groups com- 

 monly designated as soft-rayed fishes leads one to wonder 

 at what appears to constitute an exception to the rule 

 of the absence of fin-spines among these forms. There 

 is no doubt about the rigidity, sharpness and efficiency 

 of catfish-spines as organs of defence. They appeal to 

 one as true functional spines whatever may be their 

 nature in a structural way. 



Observations upon the microscopic structure and de- 

 velopment of catfish spines leads one to the conclusion 

 that while they are strong and sharp spine-like struc- 

 tures in function their nature in a morphologic way is 

 not such as to be considered widely different from that 

 of soft rays. It has been noted above that the spines 

 of the more highly modified fishes are regular with re- 

 gard to surface. Quite the reverse of this state obtains 



