Tnmciis Arteriosus. 207 



V^ = first valve. 



V- = second valve. 



p = papilla on wall of Pylangiuni. 



d = depression on spiral fold opposite p 



pi = papilla at Pylangial valves. 



Plate XXXV II. 



F\^. I. — Heart of //y/a aiifecr, showing no outward line of de- 

 marcation between the Pyhmgiiim and Synangium. 



Fig. II. — Heart of Liiiiuodvntiste!^ dorsa/is, showing distinct out- 

 ward line of demarcation between Pylangium and Synan- 

 gium. 



Fig. III. — Drawing of a dissection of the 'I'runcus Arteriosus of 

 Hyla aurea, seen from ventral surface. 



Fig. IV. — The posterior end of the Truncus Arteriosus of Hyui 

 aurea, showing the Pylangial valves. 



Fig. V. — Truncus Arteriosus of Hy/a nurea, showing the inter- 

 locking apparatus open. 



Fig. VI. — Truncus Arteriosus of Hy/a atirea^ dissected from the 

 ventral aspect, showing the interlocking apparatus shut. 



Platk XXXVTTI. 



Fig. VII. — Longitudinal horizontal section of Hyla aurea^ to 



show the Synangial valves. 

 Fig. VIII. — Longitudinal horizontal section of Hyla aurea heart, 



to show Pylangial valves. 

 Fig. IX. — Truncus Arteriosus of IJninodyiiastes dorsalis, to 



show Synangial valves. 

 Fig. X. — Truncus Arteriosus of Linniody)iastes dorsalis, to show 



Pylangial valves. 

 Fig. XI. — Longitudinal Horizontal section of Truncus Arteriosus 



of Lininodynastes dorsalis, to show the Synangial valves. 

 Fig. XII. — Truncus Arteriosus of Heleicporus pictus, to show 



Svnanofial valves. 



