48 ro.MI'AKATIYK AXAToMV. 



SV;KMKHT,, M. B.//TV>>- ~.ur Anat. '///'/.,,/. Mnrplio!. Jlirl>. IX., 1884. 

 WiKiiKusiiKiM, K. Salamandrina pc/-.^>/.-,7,'./' 



Salamandrinen. (lonua, 1875. (Annali // .)///.< . civico. V.>1. VII.) Die 

 tfomi der Gymnophionen. Jcim, is? 1 .'. . '<! ml I 4'/n von 



Lepidosiren awnectens. Morphol. Sfa . I left I. Joiia, 1880. 



II. RIBS. 



The ribs, standing in the closest connection with the rnyocom- 

 mata (myotomes) of the great Literal muscles of the body, are 

 arranged segmentally, and onto- as well as phylogerietically^pass 

 tlirough a membranous, a cartilaginous, and a bony stage. Tlieir 

 development, \\liidi ;is a rule takes place first in the anti-rim 1 part 

 of the body and then extends gradually backwards, is usually 

 entirely independent of the veitebral column, their connection with 

 it being a .secondary one. 1 



Fishes and Dipnoi. The cartilaginous or bony ribs are 

 attached to the basal processes already described, and extend 

 Yentro-Iaterally from the corresponding vertelmei The 

 ribs of Fishes show a very primitive condition, usually^cxtending 

 almig the whole length of the vertebral column (Lophobranchii, 

 Spatularia). In rare cases they are absent, though many Fishes 

 only possess rudimentary ribs (many bony Fishes, Elasmobranchs). 



In others, as in numerous Teleosteans and Ganoids, they are 

 very well developed, and encircle the body-cavity like the hoops of 

 a cask ; but they never unite together in the mid-ventral line. 



The relations of the anterior portion of the vertebral column to the auditory 

 organ in certain Teleosteans will be described later (see p. 207). 



Amphibia. In the ribs of Amphibia there are evident 

 signs of degeneration ; as a rule they are confined to the region of 

 the trunk, or at most they extend in certain Urodeles in a very 

 rudimentary form as far as the first two caudal vertebrae ; in other 

 cases, as in the tailless Batrachia, they are so remarkably short 

 that they can no longer be said to encircle the body-cavity. In 

 many An ura the ribs are not distinctly articulated, as they become 

 fused with the broad transverse processes (Fig. .S2, 7?). 



Tlio rili- 1. 1 I'rodeles are forked at their pn>xiiiinl ends, and articulate with 

 the bifuivated t ran^vt-rse processes of tin- \crtclii 1 ;! 1 . The ventral linil> only .>[' 

 the transverse pru.-e.-s rurrespmiils t<> the basal pn.ress nf ( iaimids : the dorsal 

 one i- t" ! l<>"keil ii]i]i as a iieonnirph. The liil'mvated ends of the ribs in 

 Kept ilea and I'.irds as well as the double art irular facets "I' the ribs of Mammals 

 an- to be explained in the same manner. 



1 The lil^ of < I.-lHiijils, MMil ]inssili'y IlKii thnse nf Ilj|i||iii. ^eelll to I'nlh.W ;IU 

 y dillelTIlt ]'hlll of development, 111 that tlnV hi-enliie seelllrllti il nil' tlelll |)](> 

 In WIT ;irrhr N B8 liii-litiniieil in tin- rli:i|>ti-r nil thr Vel'ti-hnil cnllllllll. 



