I02 WOODWARD : FOSSIL STURGEON OF THE WHITBY LIAS. 



This is shown, of one-third the natural size, in the accompanying 

 fig. I. It is a long bone, constricted in the middle, and with a 

 triangular expansion at each extremity ; the upper portion being the 

 smaller and compressed antero-posteriorly, while the large inferior 



Fig. T. Right hyomaiidibular bone of Gyrostcus mirahilis, lateral aspect (A) 

 and posterior aspect (B) ; one third natural size. 



expansion is compressed from side to side. The bone agrees in 

 shape exactly with the corresponding element of the living Sturgeon 

 (fig. 8.;), but in the latter the greater part of the lower expansion 

 remains unossified ; in Gyrosteiis, indeed, the ossification is only 



Naturalist, 



