The general plan is very similar to that found in the majority of Salientia (E. M. and N. G. Stephenson, Szarski, 1947), only a few points deserve special attention.
A. coeliaco-mesenterica is given off from the ventral aorta about 1 mm. caudad from the point of union of the right and left thoracic aortae, as in Bombina.
A. mesenterica caudalis was present in all three animals investigated. The Stephensons give to this artery the name of the anterior haemorrhoidal.
The middle sacral artery (aorta caudalis) was present in all specimens. The origin of this vessel is, however, different from that described in other species, as it does not branch from the abdominal aorta but from the right or left common iliae artery (Fig. 1). The Stephensons figured this vessel in their diagram of the arterial system (Plate 43), but did not, however, notice its homology with the caudal artery of the tadpole and adopted the name “posterior haemorrhoidal artery.”
Text Fig. 1. The branching off of the middle sacral artery. A.caud., aorta caudalis; A.il.comm., a. ilica communis; A.mes.caud., a. mesenterica caudalis; Aor.ab., aorta abdominalis.
As stressed by the Stephensons, the large cutaneous artery is a spacious vessel. Its diameter equals the diameter of the pulmonary artery. It runs in a cranio-dorsal direction, surrounds the scapula craniad and divides into three vessels very similar to those found in Rana esculenta, namely: ramus lateralis arteriae cutaneae magnae, r. auricularis a.c.m., and r. dorsalis a.c.m.
R. lateralis a.c.m. corresponds to the continuation of the large cutaneous artery in Bombina, Pelobates and Bufo (Szarski, 1948). It runs caudad directly under the skin which it supplies.
R. auricularis a.c.m. runs craniad exactly as in Rana, reaches the skull and bends in a curve ventrad, finally supplying the thymus and the muscles of the mandibular joint. It does not, however, anastomose with the temporal artery, as in Rana and Bufo.
R. dorsalis runs dorsad as in Rana, and supplies the skin of the back and of the dorsal surface of the head.