PLATE I 



EXPLANATION OF FIGURES 



5 Reconst ruction of the heart of a 7.9 mm. embryo. The right atrium and 

 right ventricle have been opened fi'om the right side, the cut passing through 

 the junction of the transverse part of the sinus venosus {Sn.t.) and the right 

 sinus horn (Sn.d.). Magnified 25 diameters. 



6 Reconstruction of the heart of a 15.2 mm. embryo, thd right atrium and 

 right ventricle opened from the right side. Magnified 25 diameters. 



ABBREVIATIONS 



A., Aorta dorsalis 



Ao., Aorta (ventral part) 



A.d., Atrium dextrum 



A.S., Atrium sinLstrum 



Bulb., Bulbus cordis 



Cr.ter., Crista terminalis 



En.s., upper endocardial cushion 



End., lower endocardial cushion 



En.c, fused endocardial cushions 



•ulan 



L.V., Limbus fossae ov 



O.I, Ostium primuin 



O.II, Ostium st'cuiulun 



O.iu., Ostium intorvcn 



Per., Pericardium 



S.I, Septum primum 



S.II, Septum secundum 



S.in., Septum interventriculare 



Sn.t., Sinus venosus, trans, part 



Sn.d., Sinus venosus, right horn 



S.sn., sinus septum 



s (Vieussenii) 



Sn.cor., Sinus coronarius 

 Sp.in., Spatium intersepto-valvulare 

 Sul.in., Sulcus interventricularis 

 T.vv., Tensor valvulae = Septum spu- 



rium 

 Vv.v., Valvulae venosae 

 V.v.d., right valve 

 V.V.S., left valve 

 V.f.o., Valvula foram. ovalis 

 V.car.c.d., right com. card, vein 

 V.car.c.s., left com. card vein 

 V. car. a.d., right ant. card, vein 

 V.car.p.d., right post, card, vein 

 V.C.S., Vena cava superior 

 V.C.I. , Vena cava inferior 

 V.az., Vena azygos 

 V.scL, Vena subclavia 

 V.h., Vena hepatica 

 X, (fig. 9)= part of right sinus valve 



guarding coronary orifice 



368 



