OCR Text |
Show CHAP. IV. DOMESTIC RABDlTS. 118 , f tl occiput, instead · l 1 tform " 26 0 10 . . . of "tho S(]lJaro rmsoc p a . tl o wild rabbit, I· S m· mo st postonor margm . ro"octing slightly as m ~ intod as in ftg. 9, C. of be in"" h'UUcatect, 01 P J lop-oared rabbJts po · ' 1 to tho size , o to'ds rolatJvo Y , , Tho pammas 1 ' • lly much thicker . ' Ill' of tho skull arc gono~~t ;:.---""' -='"-"/ · _) . l 'lclmbul · than m t 10 WJ . (fi 10) presents ~ ThooccipitaHoram.~ lg. . · tho ; 11 differences . m - { some romarka) o . od o between tho .1/ wild rabbi~, tho ~~~l~~·abl; and almost - ;. condyles JS co l out and tho upper ~ an!!Ularly hollowoc ' 1 otchod · , I "' • deeply and square y n ' ~ _';/_ . ...--(! , ', , edge IS aitudinal axis exceeds tho ~--" - ~~_-~ :.:. . ht.e nce othrsoo loanXt;J> s. In tho skulls of th·o --:;;.-- . :!...-_-o.... Y,, ransv bb't tho transverse aXJS · · 1 oared ra 1 s , I op- tho longituwnal ; for in none ' ' J exceeds . tl lower edge be- - . of those skulls. was 10 l hollowed ' malic Arch, showing the tween tho condyles so deep y . Fig. s.-Pnrt of Zygo I bone and tho . fi of them there was no upper . tmg end of the ma,lr . V r out. lD lVe • t. P' oJec t . or mltuml size. ppe ' t l . throe there was a race auditory mea ~bbtt Lower figure, Lop· square no c 1, lD . 1 0 it was well figure, Wild . bb t f th notch and m two a on cared, hare-coloured Ril ' . o o f" t'h foramen aro remarkable, volo cd. Those differences in tho sh. apeo r0t ant ea structure as t b o spm· a1 dcoon s1. dPo n··n g that it gives passage to so IIDPm au, · ow , though o.pparontly the :ffi t d B c outline of the latter is not a oc e A by tho sho.pc of the passage. In all tho skulls of tho largo lop-cared rabbits, tho b_ony auditory meatus is con~picuous~y larger than in tho Wl~d rabbit. In a skull 4·3 inches m lengt~, . fSkull ,ofnaturnl size, showing nd which barely exceeded l~ Fig. 9 - Poste• w~ cln~~~~e A Wild Rabbit. 13 Feral ~ . dth tho sJ-ull of a wild rabbit the mter-pan a · 1, S nto ncar M11d tra. urea ' '- . l th) Hubblt tt om Island of . a • (wlrichwas3·15inchesm eng ' c LmgeLop·emed llnbbtt.. . , t Tho orifice . catus was exactly tWice as grca . tho longer diameter of th? m . in on tho side nearest tho skull ~tands up is more compressed, and Its marg higher than tho out~r side. Tl~o A B whole meatus is direct~d more forwards. As in brcodmg lopoared rabbits tho length of the oars and their consequent loppin~ and lying flat on tho face, , tl chief points of excellence, . . arc 10 d ubt that . - cci ital Foramen, of natural stze, m- thoro can hardly be~ o ·, , Fti_ l~il~l{a~bit; H. Largo Lop-cared L~bbtt. tho great chango m tho ~~z~, 1 t· ol to this same p::nt m form, and direction -of the ~ny r::tui :~l:c~~ony of individuals having the wild rabbit, is duo to t o con ue 25 Waterhouse, 'Nat. Hist. Mammalia,' vol. ii. P· 36. CII.A.I'. IV. DIFFERENCES lN TIIEIR SKELETONS. 119 larger o.nd larger cars. Tho influence of tho external ear on the bony mco.tus is well shown in tho skulls (I have examined three) of half-lops (sco fig. 5), in which one car stands upright, and the other ancl longer car ho.ngs down; tor in those skulls thoro was a plain diftoronco in tho form and direction of tho bony meatus on tho two sides. But it is o. much more interesting fact, that tho changed direction and increased size of tho bony meatus have slightly affected on the same side tho structure of tho whole skull. I hero give o. dramng of tho skull of o. half-lop; and it may bo observed that tho sutmo between tho parietal o.nd frontal bones docs not run strictly at right angles to tho longitudinal axis of tho skull ; tho left frontal bone projects beyond tho 1·ight ono ; both tho posterior and anterior margins of tho left zygomatic o.rch on tho side of tho lopping oar stand a little in advance of tho conesponding bones on the opposite side. Even tho lower jaw is affected, and the condyles aro not quito symmetrical, that on the loft 8tanding a little in advance of that on tho right. This seems to mo a remarkable case of correlation of growth. Who would ho.ve surmised that by keeping an animal during many generations under confinement, o.nd so leading to tho disuse of the muscles of tho cars, and by continually selecting individuals with tho longest and largest ears, he would thus indil'cctly have affected almost every suture in tho skull and the form of tho lower jaw! :Fig. 11.- 'kull, of natural size, of Half-lop RablJ!t, showing the different direction of the auditory meatus on the two sides, and the consequent general distortion of the skull. The left cnr of the animal (or right side of figure) lopped forwRrds. In tho large lop-cared mbbits the only difference in tho lower jaw, in comparison with that of the wild rabbit, is that the posterior margin of the ascending ramus is broader and more inflected. Tho teeth in noithor jaw present any difference, except that tho small incisors, beneath the largo ones, aro proportionally a little longer. Tho molar tooth have increased in size proportionally with tho increased width of_ th~ s~, meo.sured across the zygomatic arch, and not proportionally With Its mcrcascd length. Tho inner line of tho ·ockots of tho molar teeth in tho upper jaw of the wild rabbit forms a perfectly straight line; but in |