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Show 162 ON THE STl~UCTUR.E OF rriiE SI\:ULL. KE Ol\1PARED S'I'RUOri'UHALLY AND THE SKULL OF THEENPITALi L y 'VITH THAri' OF 1\lAN. DEVELO Pl\1 i . 1 os"essino· a bony skeleton, osseous IN the series of anima s p ::~d d aos the xtrenle terms ; and be r O'ar <=> c fishes and man may b ~ fish tho Pike-for com- 1 t the skull of an osseous - I n?w se ~c - . f Man Whatever community of strueture pan~on with t:a~:ese m~st be expected to persist throughout obtal~S betwe~ . . while the differ nces between them the Intermediate terms' . d . b the subsequent will be more or less completely bndg over . y ::> . 'l ~ ncl study of the skulls of the lower Mammals, Buds, h ,eph es, a Amphibians. f .1 (F' 65) presents the 1nost At first sight, the .Jcull o a pl ce . Ig. Fig. 65. A--/ An SyPr.Ojt Brg · ) p f prefrontal ; II. M., hyoF' 65 Side view of the skull of a Pike (after AgassiZ .-1 ' '. I Op inter-operculum; Jg. m~ndibular bone; Op., opercublum \~· ~P·:tls~~~;~~e~~~' us;l~pl~cti~; JJtft, metf-~:er}y" Pr.Op, pre-operculum; J!rg., ranc lOS egd. t ~ .Ar Mtieular; An, angu al' ' O'Oid. Pt palato-pterygOJd arch; Qu., qna Ja um' ' dent~ry; 's. Q1·., supra-orbital bone. THE S1'HUC'rUHE OF THE PIKE'S SI\:ULL. 163 striking dissimilarity to that of a man. The skull proper is flattened, narrow, and elongated, its vertical height and transverse diameter being ·insignificant when compared with its anteroposterior length, the predominance of which is due chiefly to the disproportionate enlargement of tho anterior half of tho cranio-fac.ial axis, i. e., the presphenoidal and ethmo-vome1·ine regions. ~rhe brain-case is relatively very small and 1nuch depressed, instead of presenting the capacious dome of the human skull, while, on the other hand, tho f<.wial apparatus is very large and complex, and its compouents 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 connected with the latter by the intermediation of a complex, mobile, suspensoria! apparatus (Fig. 65, HM. to Qu.), which articulates with the skull above and with the lower jaw below. A part of the same apparatus gives attach1nent to tho 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 trausvorse and vertical section be taken through the pike's skull, so as to traverse the organ of hearing, and to divide the suspensorium longitudinally i'h.to two parts, the posterior and anterior moieties of the skull will present the appearances represented in :Figs. Go and 67. The posterior segment (Fig. 66) is obviously com parable with the corresponding segrnent 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. ] urthermore, certain of the bones ( Ep. 0, Op. 0, &c.) which entor 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 tho inferi r arch is connected. The anterior segment (Fig. G7) presents a similar general c01~respondence with the corresponding segment (Fig. 48) of the Man's skull. 'That is to say, there is a flool' with which is con- M 2 |
