40 



ALLEN 



(Text-figs. I and 2, and PI. VI, fig. 39 ; C.T.) and an inner coat 

 composed of muscle bands, the trahecidcE carncB (PL VI, fig. 

 39; T.C.A.). These muscle bands run in every direction, but 

 mostly dorso-ventrad, and between these bands there are large 

 blood cavities, which increase in size toward the central cavity, 



Fig. I. 



the muscular layer becoming more and more compact toward 

 the surface. The central cavity occupies a large portion of the 

 auricle and is continued into the posterior lobes. Penetrating 

 the floor of the auricle, a little caudad of the center, is the anri- 

 culo-ventricular opcnino- (PL VI, fig. 39: AA'.O.), through 



