PLATE III 



Fig. i . Microphotograph of longitudinal section of a much contracted 

 oval in the swimbladder of Myctophum punctatum ( x 120). Note 

 the many blood vessels running through the relaxed tissues of the 

 oval, mostly consisting of the submucosa. The radial muscles of 

 the oval (rm) may be clearly seen. An arrow in the main cavity 

 of the swimbladder points to the almost completely closed opening 

 of the oval. 



Fig. 2. Radiographs of Trisopterus minutus (above) and Lionurus 

 filicauda (xi), Note the very much sharper appearance of the 

 bones of the former. 



