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The sternum of the Ranidae is supposed to have been formed 
out of the aforesaid paired first formation. At another place G6rTE 
sums up his theories in the following way: the amphibians have no 
costal sternum. Its place is taken up by skeleton-parts of various 
origin, viz. 1°. by cartilage, formed in the linea alba abdominis and 
in the tendinous band of the m. rectus abdominis, which has to be 
considered as homologous with ventral ribs, and 2°. by cartilage 
formed in the membrane interepicoracoidea, there where the latter 
is inserted to the part spoken of sub 1°. the sternum of urodela 
and that of Bombinator (arcifera) consists of both parts. The sternum 
of the Ranidae (firmisternia) is supposed to have been formed only 
out of the part named sub 1°. the part formed in the membrane 
interepicoracoidea is considered by Görrr as belonging to the bumeral 
zone. 
The results of WirpersHeim’s researches may be summed up as 
follows. In the formation of the (paired) sternal formation neither 
in Anura nor in Urodela the humeral zone has any share. The 
whole development of the sternum takes place in, resp. between 
the muscles of the wall of the body. In the Amphibians, too, one 
has to speak of a costal sternum, for why should ventral parts of 
the myocommata that are becoming cartilaginous have to be con- 
sidered from another morphological point of view than the ribs 
lying near the spinal column? 
Let us sum up the facts found by Görrr and Wieprrsueim. In 
the first place the sternum is formed pairedly and in the second 
place it is formed loose from any previously existing skeleton-forma- 
tion, in so far the theories agree. Only the interpretation of the 
facts is partly different. Görrr as well as WinpursHeim speak of 
ventral ribs. WrirpersnHeim brings back the whole of the amphibian 
sternum to ventral ribs. Görre is in favour of a coracoidal origin 
for a large part of the sternum of the Urodela and that of Bombi- 
nator (arcifera), as well as for the whole sternum of the .Ranidae 
(firmisternia), only because it grows in the membrana interepicora- 
coidea. But after all neither of these interpretations can explain 
away the fact that the first formation of the sternum of all amphi- 
bians if formed quite independently, in other words that it is 
authochthonic. 
Consequently there is a genetic similarity between the sternum 
of the amphibians and the prosternum of the sauria; so they are 
homologous. The costal xiphisternum of the sauria is the ontogene- 
tically as well as phylogenetically later formed sternal element. The 
value of this homology is not diminished by the fact that afterwards 
