ip. 



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244 lULLKTIN :!l, rMTKI) STATKS NATIONAL MISKIIM. 



sciilu'd (<(iilcti) tlicni aro four (!iiililaf;in(»iis iirclics hclow the cerato- 

 bniiicliials, wliicli beloii-; to the tleniial system, and wiiich are ealU-d ex 

 trahram-hials, IMoxiinally tlic lirst of these is artieiihded witli the an- 

 terior exterior aiiyle of till' livohraneliial pli'.te. Dislally the four are 

 nnited to<,H'lher. Tliese arclies snpjMtrt a system of branchial frinj^es, 

 wlneh are internal in position, and are eontradistinjiiiished from the ex- 

 ternal braneliia' which the Salient ia exhibit when lirst hateiieil, and 

 which are the<»nly branchi;e of the I'rodele and oth«'i' tailed types. They 

 are thought by llnxley and Tarker to lu^ hom(>h»^'<»ns with the branchial 

 strnctnres of the Marsipobranchii or lampreys. ([Mat(^ r»l, ti^-. 1.) 



The di've!(»pment of the anditory ossicles and c;ii tila.i;es exhibits the 

 followinj;' facts. Tiie epistapedial disk appears in its noiinal posititm, 

 eoverinj-- the tiexure of the (pmdiate cartiiajne, 'I'lie inlcrstapedial ap- 

 l»ears as a bad in lioid of and distinct trctin the stapes, and the nii so- 

 Hta]>edial appears as a small menduane on its apex. At a period «d' its 

 growth the intcrstapcdial caitilage c(»iiiiccts the stapes with the (piad- 

 rate cartilajut', as in Tiematodcra and larval i'scinlosanrian I'rodela. At 

 the same time th(^ ceratt)hyal aiticnlates with the quadrate more dis- 

 tally, so that at this stage a liana presents the characters of a transi- 

 tional stage seen in (he salamandrine gt-nera Hiieleipcs and I'lethotlon. 

 The inteistapedial then elongates nntil it reaches theannnlns tympani- 

 cus. These liuts go (o show that the intcrslapt'dial and iiu sustajiedial 

 are not segmerited t'rom the ceiatohyal (>i' meckelian ar<;hes, and are 

 therefore not homologons with the <>ssi<'iil(i 'f»'//7*rs of mammalia, unless, 

 imUrd, Mie end)ryonic lei^trd has iiccn greatly falsilied i»y ca'iiogeny. 

 (Plates 1J», .".().) 



oiiKJiN AM) i:v(>i.i'i'i<).\ OF 'I'lii; sm,ii;ntia. 



The oldest Salientia of which we ha\e any knowb'dge were obtained 

 from the .hirassic iieds ot' the iiottky .Mountains by i*M)fcss(»r Marsh.* 

 Tliey occur in lower iM>cene beds in North America ((Ireen lJi\er 

 shales)! and in Middle .Miocene (»f Switzerland ( l'lppel.'«hc;m)| and (ler- 

 maiiy (Ibaiinkohle of the Kliinc).^ They are not rare in the (pper Mio- 

 cene of North America (liOup l'oik,of Kansas). || Fitrms which by their 

 8tru(!ture would c( unect this onb'i' directly with the extinct onb-rs 

 are uidaiown. It is, Ihtwevei', entirely probable that, as already |»ointed 

 out (p. II), the Salientia were derived from the K'lnK^hilomi, but whether 

 the Stegocephali enter the hue or not is uncertain. The compacted in 

 lerior j)'. Ivicelenu'nts without(d)turator foramen otthe Salientia is much 

 like the sanu' condition in the IMiachitomi, and to produ(!(^ an almost 



* I'rofcf,!. liiiti^li Ac. Sci., 1"-T, MhiiIi'ch ; dm llic cn iiliiici' riinii.-ilMMl liy l>|-. Olio 

 M.-ycr. 



t('oi>t', l\'i'i»l. i;. S. (ii'ol. Siirv. 'rcns., Ml, l--:., \). 100. 

 tTNuliiiili, (Miissil. <l. iSiiiiiiilii.T, 1^;;h. 

 ^ \im MryiT, l';il;i'iiiiliiirniiilii(ii, IHiid, )>. I\>;{. 

 l|{'oi»f, .Viiici'iiiiii .Naliiralist, issd, p, i|l. 



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