48 The Life Story of the Fish 



to the end of the backbone. It has a series of gill arches which 

 support the breathing apparatus. In the higher animals these 

 have come to form part of the voice-box. Further, and this is 

 one of the fish's most noticeable features, it has no neck. It 

 has a tail, extending from the caudal fin forward to the vent, 

 which is just in front of the anal fin. It has a body, extending 

 from the vent to the gill opening. And it has a head, extend- 

 ing from the gill opening to the front end. It even has 

 shoulder-blades, strange as that may seem, supporting the 

 pectoral fins, but in most fish these attach to the top of the 

 head. It was not until, in the land animals, the shoulder- 

 blades moved back and relinquished their hold on the skull 

 that room was made for a neck — a visible separation between 

 head and body. 



What makes the trout a low fish, in so far as the skeleton 

 is concerned, is that the pelvic fins are located far behind the 

 pectorals and have no connection with the rest of the bony 

 structure, that all of the fins are made up of soft rays with 

 no spines, and that the bones of the head are primitive in 

 number and position.^ 



If we compare the skeleton of the trout with that of such 

 a fish as the perch — to pick one low in the scale of the sports- 

 man but high in the scale of the ichthyologist — we find dif- 

 ferences. Most of the fins have stiff spines in them as well as 

 soft rays, and there is a general tendency to an unfriendly 

 spininess all over, from the spikes on the side of the head 

 to the microscopic teeth on the after-end of each ctenoid 

 scale. Ichthyologists consider this a specialization and, there- 

 fore, an advance. More conspicuous, though, is the propin- 



^ The bones of the fish's head are highly sigriificant, and their persistence 

 and evolution through the amphibians and the reptiles to the birds and 

 mammals are extremely interesting, but too many erudite men have written 

 too many large books on the subject to make it possible to treat it super- 

 ficially, and it is too involved to treat seriously here. Therefore, we shall 

 say no more about it. 



