SEA-FISHERIES LABORATORY. 



313 



to a position much nearer to the ventral surface of the 

 skull, and this is also the case with the bones of the 

 upper jaw. But otherwise all are quite normal. The 

 difference in the two skulls lies in the lower jaw. In the 

 normal skeleton this consists of the usual parts, dentary, 

 articulare and a very small angulare, and is rather 

 massive. In the abnormal skull these parts are 

 altogether different and are much dwarfed. There 

 is no apparent angulare, but, perhaps this is 

 ossified together with the articulare. This element 



PREM AXILLA 



HYOMANOIBULAR 



BOPERCULUM 



DENTA 



ARTICULARE^^ T\ PREOPERCULUM 



ansu'lAreX 'SYMPLECTIC 



QUADRATE 



Fig. 21. Skull of Trigla gumardus. Natural size. 



is not at all like the normal bone ; it is an 

 irregularly shaped bone the long axis of which is dorso- 

 ventral. On its posterior surface is a saddle-shaped 

 articular surface which receives the articular knob of the 

 quadrate. In front and a little above this is a socket- 

 shaped articular surface into which the proximal end of 

 the lower jaw proper fits. The latter consists of an 

 apparently single bone, which is a flat hoop forming the 

 lower margin of the gape. It probably is the fused and 

 completely ossified Meckelian cartilages, whether or not 



