Till-. KNDOSKKl I H >N 



[69 



tnaining mr.uhsiautiaicd h\ .1 pai.die! series ol embryonic 



, ic ,i , iip.ni ;ni Insecure foundation and is liahie t<> n- 

 ceive eMiiMderabie mndiiicatiMM tin-.>n;;ii the discovery of ad- 

 ditional farts. In Iraeiii!; thCM hlStOfitfl MIC anleiiMi- ;ui.l 

 posterior linih;. innM he lic.ilcd '.epaialelv, Miiee, allliMiii-li the 



free innir, are pi.miK serially homologous, and often corre- 

 spond <|inie closely, p. HI I'M i p. nt, the girdles, .iiiiiMm-ii equally 



;i PMIIJMII of Mie appendieiilar skelelMi I, dillei I in idaniental] V 

 I'rMin one aiiMtlier ;ind must have li.id ;t ;-Mincwli;il dil'lVi cut 



c.ni\ history, 



Beginning willi ili- poitlfrior liuih, which is more conserva- 



livc tli;iii MIC ;iiilcriiM\ :ind J)|M|.I|,!V icl.ini'. IIIMIC piimiiivc 



characteristics, it ni.-iy .s.iivi\ i>c Mippi.-,ci Mcit .\\ its origin as 



;i Inc.-ili/cil ll.ip '!' ;i Miicc cmil iiinmis tin fold, its skclctnii COH- 



sisted of .1 series "i" spines or rays, independent f pne another, 



.ind SMIIICU li.il liuit;c|- ;il then h.r.cs, t;i|)criiii; tn thcii h<<- 



extremities ( I'JK'- 43i a), To insinc strength ;nid i. ^-ain a 

 concerted action, ; very n.itm.d stc|> \\<mii he t.. widen these 



.-it MICH bases siiii fiirMic-r until Miev fuse, Forming a piece 



s elhiiii; like ;i mini), with IMII:; teeth I'.ii' ;ip;nt ( hi;; ,| ^, h). 



As these or^;iir, become (| l ''I'll greater inipMil.nn-e ;ind need 

 ;i liinier BUppOlt, lite h.r,;d pMiliMir,, Corresponding !> the 

 backs <if MIC (Minhs, would be likely to ^rnw inwanl-; until 



they meet ;nid fuse across the nud \cnti.d hue, iinr. forming 



a \ei \ primitive girdle, with whieli the free p;ul wnnld become 



tnOVabl) aili< nk-ited ( \'\^. 43, c). Tlii-, kr.l Cfl 6, Is, however, 



IIM| ;i liypMMielie;il nnc, hut dr.'iwn diieeMy I" i the posterior 



i;hdle ;nid l"i ee linih .-.kch-tmi nf the dog-fish, B fcypfcal C 



lachian, in \\hi.h tin- free iimi consists of a b&ripterygium f 

 bearing a scric of rays, the wimic hem" IHM\ .ihl\ .-III.K hed IM .-i 



girdle in the I'MTHI ..f a vend.d hand. AlMiou^h there is at 

 pi.- rnl ;m impassahle SpaCC helween the, free linih an<l that 



M|" even iiie simplcBl amphibian, iiie girdles <d" MIC two forms 



are UMI BO fai apart, since a hi-.-adenin^ <.f MK- middle piece 



int. i a plate, and the < \ leu .. ,11 ..I" il , did' <|..r-,;dly until they 

 Come in CMiilact with a pair "f ribs, would ennvcit the one 

 into the Mlher. (Cf. l r i^. 44, (1.) 



