510 



ANATOMY OF VERTEBRATES. 



of Birds. 1 The apex of the ventricle is attached by a short fold 

 of the serous membrane to the pericardium, fig. 336, t. 



337 338 



A' 



339 



a 



a 



Structure of ventricle, Emys europcea. xxxvm. 



In all the foregoing modifications of the reptilian heart the 

 venous blood from the general system and the arterialised blood 

 from the lungs are transmitted by distinct auricular reservoirs 



into the ventricle, where, 

 through the spongy character 

 of the receptacle, and the free 

 intercommunication between 

 the basal spaces into which 

 the auricles open and from 

 which the arteries proceed, the 

 blood is transmitted, in a more 

 or less mixed state, to the 

 lungs and to the general sys- 

 tem. 



In the Crocodilian order a 

 marked advance is made in the 

 structure of the heart. The 

 blood from the general system 

 is poured by the veins into a 

 sinus, fig. 339, s, whence it 

 passes into a right auricle, ib. 

 o, by the usual bivalved aper- 

 ture. The auricle has a more 

 distinct t appendix,' and its mus- 

 cular walls are thicker than in 

 lower reptiles. The auriculo- 



l.'i 'lit auricle and ventricle, Crocodilus acutua Ventricular Orifice ig defended 



1 xx. vol. ii. p. 48, prep. no. 920. 



