2,2,6 BRUNER. 



EXPLANATION OF PLATE XV. 



Fig. I. Heart of Salamandra maculosa, viewed from the right side. The 

 perforations of the septum atriorum are not indicated. 



Fig. 2. Heart of Salamandrina perspicillata, also viewed from the right side. 

 Septum atriorum and pulmonary vein are wanting. 



Fig. 3. Frontal section through the heart of Salamandra maculosa. The 

 plane of the section passes through the anterior part of the sinus-atrium valve. 

 The spongy structure of the ventricle is not shown in the drawing. 



Fig. 4. Section a short distance behind Fig. 3, and from the same series. 

 The transverse portion of the sinus-atrium valve and the dorsal margin of the 

 sinus opening lie in the plane of the section. 



Fig. 5. Section through the conus arteriosus and spiral valve of Salamandra 

 maculosa. 



Fig. 6. Frontal section through the heart of Plethodon erythronotus ; the 

 direction and location as in Fig. 3. 



Fig. 7. Frontal section through heart of Plethodon erythronotus ; correspond- 

 ing to Fig. 4. 



Fig. 8. Conus and spiral valve of Spelerpes fuscus. 



