330 AlVATOMICAL TECHNOLOGY. 



placed portion of the left auricle. Entad its walls are smoother 

 than those of the appendix, and into it open the YV. pulmonales. 



§ 877. Sinus coronalis s. cardiacus, sn. cor. s. crd. — The sinus 

 of the coronary vein. — This is not distinctly shown in any of the 

 figures. Its position is indicated on Fig. 91 by the abbreviation 

 y. crd. Both the sinus and the semilunar valve at its opening into 

 the auricle are readily found by examining the dorso-caudal angle 

 of the auricle close to the septum. Into the sinus open not only the 

 principal Y. cardiaca, but one or two smaller ones. 



§ 878. Sinus Valsalvae, sn. Yals. — One of the six sinuses of 

 Valsalva (Fig. 92, 94, 96).— There are three of these at the mouth 

 of the aorta and that of the A. pulmonalis. Each sinus may be 

 described as an enlargement of the base of the vessel occupying a 

 little less than one third of its circumference. Each is partly cov- 

 ered by a semilunar valve (§ 882), and is thus open peripherad but 

 closed centrad or toward the ventricle. As in man, they may be 

 designated as approximately dorsal, dextral and sinistral in the 

 aorta, and ventral, dextral and sinistral in the pulmonary artery. 

 From the right and left aortic sinuses arise the two AA. cardiacce 

 or "coronary" arteries. 



§ 879. Trabecula tenuis. — This name is applied, provisionally, 

 to a slender and apparently fibrous filament which, in the prepara- 

 tion from which Fig. 98 was taken, spans the right ventricle near its 

 apex. Its septal end springs from an independent little muscular 

 elevation ; its lateral end is attached to the base of a columna car- 

 nea. In Fig. 98 it is represented much too large ; it is really hardly 

 thicker than a spider' s thread. Can it be the insignificant repre- 

 sentative of the "moderator band" of Ruminants (RoHeston, B, 

 25-35)? 



§ 880.. Tuberculum Loweri— The tubercle of Lower.— This and 

 the Eustachian valve, both of which have been described in connec- 

 tion with the/ossa ovalis of some Mammals, we have not yet deter- 

 mined the distinct presence of in the cat. According to Hj'rtl 

 (A, 290), the former rarely if ever appears in the human heart. 



§ 881. Valva bicuspis, vh). hie. — One of the two bicuspid or 

 mitral valves (Fig. 92, 93, 96, 97, 99).— As in man, one of these wide 

 valves is at the left or lateral side of the auriculo-ventricular orifice, 

 and the other is toward the septum, thus also overhanging the 

 entrance to the aorta. 



