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Show 262 FOWL. CIIAI'. Vll. bones, which arc rather short, and between these brrtnchcs and the ~Mal bonos. The surface of t'ho frontal bono, on which tho branches of tho premaxillary rest, is very litt.lo depressed. These peculiarities no d~u~t t-;t,n.m.l in close roln.tion with the broad :flattened rose-comb charactcnst1c of tho IIamburgh breed. r have examined fourteen skulls of Polish and other crested br-eeds. Their differ ncos arc ex- A traordinary. First for nine skulls of diiieront sub-broods of English Polish B fowls. rfho hemispherical protuberance of the frontal bones 68 may be seen in tho accompanying drawings, in which (B) tho skull of a white- crested Polish fowl is shown obliquely from above, w:ith tbo skull (A) of G. banlcivn in tho same position. In fig. 35 longitudinal sections arc given of the skulls of a Polish fowl, and, for comparison, of a Cochin of tho Fig. 34.-Skulls of nllLurul siz •, viewed !"rom a !Jove, u little obliquely. A. Wild Gallus bankiva. 13. WhiLe-crested l'olisb Cock. same size. Tho protuberance in all Polish fowls occupi s tho same position, but differs much in size. In one of my nino specimens it was xtromcly slight. Tho degree to which the protuberance is o ·si.fi.cd varies greatly, larger or smaller portions of bono being replaced by membrn.nc. ln one specimen there was only a single open pore; ,.cnerally, tho1·c arc many variously-shaped open sp:wes, the bone forming an irregular reticulation. A medial, longitudinal, arched ribbon of bono is generally rctn.inod, but in one specimen there was no bone whatever over the whole protuberance, and tho skull when cleaned and viewed from above w cscnted the aprmLmnco of an open basin. Tho chango in the whole internal form of tho skull is su11;risingly great. Tho brain is modified in a corresponding manner, as is shown in tho two longitudinal sections, r.s Sr>e 1\1r. 'fcgctmcicr'B rtccount, with woodcuts, of tho skull of Polish fowls, i11 'Proc. Zoolog. Soc.,' Nov. 25th, 1856. For other references, see THiel. Geofl'roy Hn.int Hilaire, 'lli~t. Uen. des Ano- 1\litlics.' tom. L p. 287. :M. C. Darcstc suspcrt8 (' Rceh rchcg sur los Conditiom de la Vic,' &c., Lillo, 1863, p . 36) thnt tho 11rotubcranco i::; not formed by the frontal bonrs, but by the ossification of the dura mater. CIIAP. VII. OSTEOLOGICAL DJF FERENCES. 263 wluch dcserv? attentive consideration. Tho upper and anterior cavity of the three wto which the skull may be divided, is the one which is so grca~ly modific~; it is evidently much larger than in tho Cochin skull of the same Rlzo, and extends much further beyond the interorbital septum, bu~ lat rally is less deep. Whether this cavity is entirely filled by the brrun, may be doubted. In tho skull of the Cochin and of all A B l!'ig. 35.-LongiLudlnul sec tions or Skull, of natural ~ize, viewed laterally. A. l'uli•h Cock. ll. Cochin Cock, sclcctctl fo1· comparison with the above from being of nearly the sume size. ordinary fowls a strong internal ridge of bone separates tho anterior from the central cavity; but this ridge is entirely absent in the Polish skull here figured. The shape of tho central cavity is circular in tho Polish and le~gthencd i~ ~he C?chin skull. The shape of tho posterior cavity, tog~thor :nth tho pos1t10n, SIZe, and number of the pores for the nerves, differ much m th?se_ two .skulls. A pit deeply penetrating the occipital bone of the ~ochm 1s cntJ.rcly absent in this Polish skull, whilst in another specimen 1t wa.o;; well developed. In this second specimen tho whole internal surface of the posterior cavity likewise differs to a certain extent in s~ape. I made sections of two other skulls,-namcly, of a Polish fowl ~1th tho ~rotuboranco singularly little developed, and of a Sultan in which t was a little more developed ; and when these two skulls were placed bet: veen the two abov~ ftgu~·cd (fig. 35), a perfect gradation in the configura:~ n of e~ch part of tho mternal surface could be traced. In the Polish ~1, w1th_ ~ small protuberance, the ridge between the anterior and nnddle caVItiOs was pre ont, but low; and in the Sultan this ridge was replaced by a narrow furrow standing on a broad raised emincmco. |