;> m 



1^ 



:ii 



r.ri.M.iiN :;i, 



IMTKI) STATI.S NATIO.NAI. MISI I'M. 



1 



,.l..vdo,.:n...l oltl.r vnlrl.n.allaiv li.^t bic.....^lv<^^.■lisl,.|iU^ 

 „.,.,.,„,„,,„,,, ,,,,,ih„. ossilifs later, m.hI attacLrs Uscll to tl.o 



r,? 



ill tii«- 



'!;;,,,,,, ,,,s,..nor -oil, funning' an o,.isll>onrlous art.cilat.mi. J lu-ro 



'",,.. ,,,, „, liist siinpl.. a. tlH- ..Miriiiily (IMatc L'O, h;.. 0), Imt s , 



,,,,„,„, ,„•„,,„.. (l.'i,. .-,), nr .itii two dibits. Tins was iirst ol.smxMl 

 bv IMMM.iii ill ISL'l ill 111.' Knn.i.rai. UcmisnUminuhit cnshita. I ro- 

 Ic'.ssm' IMiid* lii'st ..hscivnl tills in tlic .l;H/>///,s7«"Hf iH<«c/.///n« iii larvir 



„,• , , i„ i,,iinti, Tlio saiiu- lias since lurn obscrvi'il by myself in 



ISIi'l't ui.l later l.v (iiittef in liis essiiy on tlic .leveloinnent and re- 

 ..eii'eration of tl.e" Inotskeleton in Hx" tiitoii; also l.y Strasser and 

 hv Ilov ill \>iihliJxto)ii(( jHinctittiim tlie nninhers ot dif^its succeed 

 .;,,I, oilier as follows: First sta-e, li before, hind limb none; second, 

 ;. i„.,„,,. i.iiHl Imibnoiie; lliird, ;J before, liind limb 2; Ibiutli, ;5 l.o- 

 f,„,' hind limb :>. Sometimes the anterior dif-its are complete in nnni 

 l„,,.'l„.|„re the jK-sterior foot appears, and we have cunibinations of 

 ,„„„l„.rs from 1-0 to l_;i, and t— Ito the fall nnmber, l_r,, which is 

 found in alt specimens of I'.o and npwards. 



As already observed, the Uatrachia are supposed to have been de- 

 rived from t'lie Dipnoi. Spicimens ;;f L,-pi<l()siren annertais have been 

 ,1, scribed s which have the extremity of tl;e limbs abnormably bifur- 

 cate, but the iibiioriiiaiity is perhaiis in the direction of the evolution of 

 diiiits. Dr. (i. I'.nnr believes that the third, fourth, and fifth di;;its have 

 <;rown or sprouted successively in time from theexternal <listal allele of 

 Mie ulna and fibula, while' the first and second are represented by the 

 two orii;iiial branches. :| 



in the cranium a j;()od iiiaiiy important clian;;es occur before the bcnes 

 iippcar.'l Anion};- the first of these is the division of the live simple 

 tr.insverse branchial cartilaj^es ■'•, > t wo se<;iiieiits each, epibranehials 

 and ceratobranchials, or, in the c.ise of the anterior arch, into cerato- 

 liya' and hypohyal. Ho the maiidibiilar cartilaj^e immediately uiitciior 

 to the ceratoliyal, divides into the superior (iiiadiatc, and the inferior 

 iiiccUelian or mandibnlar. A snbseipient cliaii;j(! is the fusion of the 

 (piiidrate cartiiafic at its superior end with the trnbeculiiin of its side-, 

 and with the pterygopalatine arch with the inferior end. (.See IMate l>^, 

 fijis. 7-',* ) At this time the cluudadorsalis bus retreated till it is only 

 present lietwceii theexoccii»ital cai'tila.uel>elow. Whenossiticatioii com- 

 mences, the vomers, palatines, and ptervudidsare nil distinct. Towards 

 the end of the metaiiioridiosis the former two. unite, and tlu^ piery.uoid 

 separates from the palatine. Iloth these elemeiits contract away from 

 each othenintil they are widely seiiarated, and the pteryj;-oids are niiieh 



" Icoiidnrniiliit; lOiicyclopii'di'i, \H,)\. 

 t I'nicccdiiiiis I'liilii. Acail., ]>. !••'). 



I l^T'.l. 



v\ liy StciiuliicliMcl'. 



II [4eilriii;c /iir M()i|ih();;cnic d. Cnrims ii. 'I'ai.siis ilcr Vci tflMalcii, l-^T, p. I'lT. 

 liTlic fads as to I lie llrst sta';(s of tin- ?,liull of t lie ia.va of Aiiiblystoiim arc duiivud 



from JJr. W. K. I'aikcr, l'liilnso|ili. rraii>ar l-^;7, p. .Vi',1. 



