124 



miLLKTLV :!l, IT.VITKD STATICS XATIONAI, MITSKITM. 



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liii 

 •If 



i '5 



Ik 



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iiniiriiil is still ln'.iiKrliifcioiis ;iiiil possesses tlic lai'Viil toiij;'U(', clc. Tlie 

 satiii' ociiis ill S[M'Ii'r|>('s wiicii (icidiiii of its species present l>iit loiii' 

 liiini toes, as in .Miiiic.iiliis ; tlierefoio the n'lation of these two is also of 

 inexact parallelism. The relation of Thorins is also one of iiicrart par- 

 tillcli.siii, for thoMiiii its eliaractters are fonnd in some .voiui^" Sjx'lerpesat 

 an immatjire a^ne snbseqnont to the absorption of the brancliiiu, it lias 

 opisthocu'Ins vertebra'. With (Edipns, if the condition be not that of 

 cvdcl iiiiniUfli.sui with some species of Spelerpes, the approach to it is 

 close, as above observed. It is chiefly pi'cvented by the fact that the 

 ossifK^ation of the parietal bones in most species of the latter takes 

 place after the extremities are fnlly developed. It is to be ol>served in 

 tliis connection that, as has been above pointe<l out, the separation of 

 the (li<,'i(s takes j)lace at very dilferent periods in the history of the dill'er- 

 <'iif species of the same ;;(Miiis. Thus in the Sjirlirjics nihcr {hoy are en- 

 tirely distinct at a very early period of larval life, while in S. (ritlialirus 

 iuid S. hrllii, which much more nearly resembh^ the speciies of (l<Mipu,s 

 ill the ilispositioii of tiie vomerine teotli iind eylindrie form of the tail, 

 this separation is miudi retarded. 

 Tlicse ,t;eiiera may i»e parallelized also in the followiii<,' manner in 



illiistriition of the I;iw of heterolo^'y: 



I'l.inilnDo.VT.i:. 



.S'/c)'('i)(7m7«s. 



.Uiloilar. 



Hiifriirhoaeps, 



/ftmiilinliiliiim. 

 I'lclliodou. 



A. One iirciniixilijiry. 

 No fiiiit.'inellc. 



A folltiUH'IIo. 



Toes l-f). 

 Tcctli liirj^o. 



Ti'.oth small. 



Toosl-I. 



AA. Two prciiiaxillarics. 

 T(i(\s (V-'o. 



Toes iiiiitod. 



Sri3LEUri58. 



Spelerpen. 

 ManoHbiH. 



dliriiinjihihii, 

 (linlritOH. 



The minor relations may be nioie reailily expn'ssed thus 



I'l.KI llODONr.K, 



riilhodon. 

 Aiilndar. 



ffrmiihirli/Uiim. 

 Iliilriirhonrps. 



Di^MtHl-;"). 

 a. I>i;;it.s (listiiict. 



'I'wo prt'inaxillarics. 



OiH' I'ri'iiiaxijjary. 

 ^v. Diifitmiiiitcd. 



Two priMiiaxiiiaricH. 



One itrcMiiaxillary. 



DifriLsJ-l. 



Scr.l.KIJI'K '. 



Hi/riiinitliHiis. 

 S/wlirpen. 



<!rnlriln>}. 

 (KiliptiK. 



Mmu'iihiK, 



i 



'See Oriij;in oC (Jcttcra, p. .>;{. 



^Mtowr:»-u 



