384 EMBRYOLOGY OF THE LOWER VERTEBRATES OH, 



of the development of the Bird's heart are those of Greil, of which 

 unfortunately there is available so far only the abstract given by 

 Hochstetter (1906). As we should expect from the close genetic 

 relationship between Birds and Reptiles there is a close correspond- 

 ence between the general features of the development of the heart 

 in the two cases. It will suffice then to draw attention to the more 

 important points in which the development of the Fowl's heart has 



Fia. 182. Illustrating the development of the heart in the fowl. 



(Afti-r original ilra\\ in^s l>y (Iivil.) 



nt, atrium ; /'.'./, biill>o-;iiiiicular tnld ; ., conns: /../. iHt am irl- ; /./, left innominate artery; /./>, 

 IHt pulmonar\ . LF, Ifl'l vi-nt i iHi- : /.". i i-lil auiii-1--: ./. li-ht iniiuiiiiiiati' aitn 

 pulin. : ' mir aorta. 



been found to differ from that of Lacerta. S<> far as external form is 

 concerned tin- mod Mrikin^ difference is that the sinus venosus 

 loses its idi-iilit.y a- ;i <listin<-i oliambcr nf the heart. It becomes as 

 it were incorj>iMi-.| in ihc ri^lil nuriclc, all rxn-pt ils Iri'i portion 

 which persists as the cardiac end of tin- iH'i dud nl (ji\ici- ( .r 

 iiit<;rior Vena CM 



An importanl Advance up<ni llu- cnndition in Lacerta \< f.nnnl ill 

 the (livisimi of tin; ventricular part ol'tlir In-art inlna ri^hl. and a 



