TUK STRUCTURE OF THE PIKE'S SKULL. 163 



striking dissimilarity to that of a man. The skull proper is 

 flattened, narrow, and elongated, its vertical height and transverse 

 diameter bring insignificant when compared with its antero- 

 posterior length, the predominance of which is due chiefly to 

 the disproportionate enlargement of the anterior half of the 

 cranio-facial axis, i. e., the presphenoidal and ethmo- vomerine 

 regions. The brain-case is relatively very small and much 

 depressed, instead of presenting the capacious dome of the 

 human skull, while, on the other hand, the facial apparatus is 

 very large and complex, and its components are almost all 

 moveable upon the skull. Another circumstance, which at 

 once strikes the observer, is the fact that the lower jaw is not, 

 as in Man, articulated directly with the skull ; but is con- 

 nected with the latter by the intermediation of a complex, 

 mobile, suspensorial apparatus (Fig. 65, H.M. to Qu.) } which 

 articulates with the skull above and with the lower jaw below. 

 A part of the same apparatus gives attachment to the hyoidean 

 arch, and to the bones of the gill covers. 



A certain fundamental resemblance may, however, be readily 

 traced beneath these external differences. Thus, if a transverse 

 and vertical section be taken through the pike's skull, so as to 

 traverse the organ of hearing, and to divide the suspensorium 

 longitudinally into two parts, the posterior and anterior moieties 

 of the skull will present the appearances represented in Figs. 

 66 and 67. The posterior segment (Fig. 66) is obviously 

 comparable with the corresponding segment of the human skull 

 (Fig. 49), consisting, as it does, of a floor, with an upper arch, 

 which, in the recent state, inclosed part of the brain, and with 

 a lower arch formed by the various parts of the hyoidean 

 apparatus. 



Furthermore, certain of the bones (Ep.O, Op.O, &c.) which 

 enter into the composition of the upper arch are especially 

 related, as in the corresponding section of the human skull, to 

 the organ of hearing, and it is with some of these that the 

 inferior arch is connected. 



The anterior segment (Fig. 67) presents a similar general 

 correspondence with the corresponding segment (Fig. 48) of the 

 Man's skull. That is to say, there is a floor with which is con- 



m 2 



