Truncas Arteriosus. 203 



direcled inwards towards the cavity of the Pj'langium guarding 

 the entrance to the puhno-cutaneous arch, as is the case in all 

 other genera I have worked in the Australian frogs. 



The Pylangial valves (Fig. 10 viv2) are characterised by the 

 presence of two distinct papilla-like structures (Fig. 10 p.p^), 

 one at the dorsal, and one at the ventral junction of their lips. 



The interlocking apparatus is represented in this genus by a 

 somewhat thicker attachment of the spiral valve to the dorsal 

 wall, the ventral surface of Avhich is slightly rounded, so as to 

 tit into tLe curve of the spiral valve on the right side when that 

 structure swings over from the left. 



The fold itself is much less definitely spiral than that of 

 other genera. The edges are very blunt, and the main part 

 much thicker than in the case in Hyla. The carotid papilla 

 also is less well defined than in the other Australian genera 

 worked. 



2. Hehioporu.< pictus. (Plate XXXVIII., Fig. 12.) 



In Helioporus fnctus the edges of the spiral valve are 

 sharply marked and definite, and there is a decided right to 

 left spiral twist. The Pylangial valves are two in number, with 

 a small papilla on the dorsal wall of the opening, and a less 

 well-defined and smaller one on the ventral. 



TSvo synangial (Fig. 12 v^) valves are present, each of a very 

 indistinct transparent and membraneous appearance, and each 

 of approximately the same size. The right one is attached at 

 the light side to the anterior end of the spiral valve, at its ventral 

 margin, and the other end is fused with the left hand valve just 

 above the opening to the Pulmo-cutaneous arch. 



The interlocking apparatus is most indefinite in this genus, 

 being represented by a slight indentation on the fold and a 

 very slight thickening of the wall opposite it, much as in Lym- 

 nodyiiastes dorsdlis. 



3. Chiroleptts alhoguUatm. (Plate XXXIX., Fig. U.) 



In this genus the carotid papilla (car.) is very marked. The 

 spiral valve is not at all well developed, there being very little 

 spiral twist present. 



