202 THE SALAMANDER 



between the M. depressor mandibulae and the squamosal to the over- 

 lying skin and the anterior region of the paratoid, while the other 

 passes posterior to the muscle and is distributed to the paratoid 

 gland. 



(ii) R. hyomandibularis (? R. branchialis, Osawa) (a.hym.) which 

 passes lateralwards between the depressor muscle and the squamosal 

 to the surface of the muscle, when it turns, coursing posteriorly 

 across the muscle (in company with the N. jugularis — Vllth nerve), 

 to its posterior edge. It then turns round anteriorly and mesially to 

 be distributed to the dorsal surface of the M. interhyoideus pos- 

 terior, while a further branch of this artery forks around the M. 

 interhyoideus and is distributed to the posterior region of the lower 

 jaw and the tissue directly mesial to it. 



(iii) R. mandibularis externus (a.m.e.) which passes to the surface 

 together with the previous branch, but then turns anteriorly and 

 passes mesial to the jugal tendon, along which it sends a branch, 

 while the remainder of the artery is distributed to the lateral surface 

 of the lower jaw. It is a very small vessel, very much smaller than 

 the artery of the same name in the Frog. 



(iv) R. pharyngeus which passes postero-ventrally to the posterior 

 end of the ceratohyal, and then loops forwards over the mouth-floor. 

 This artery seems very variable in size and has not always been found. 



(v) R. mandibularis internus which passes antero-ventrally to the 

 mesial surface of the lower jaw. It is distributed to the skin of the 

 ventral surface of the head, to the MM. intermandibularis and inter- 

 hyoideus, passing right round the lower jaw to anastomose with its 

 opposite fellow in the middle line and also with the ramus communi- 

 cans of the sublingual artery (q.v.). It usually arises combined with 

 the mandibularis externus for a greater or shorter distance. 



(vi) A small muscular branch passing into the mesial surface of the 

 depressor mandibulae. 



It will be noticed that there is a striking resemblance between the 

 distribution of the A. pharyngea ascendens, as described above, and 

 that of the R. auricularis of the A. cutanea magna of the Frog, as 

 described by Gaupp in his Anatomic des Frosches. The A. cutanea 

 magna, however, is a branch of the pulmonary arch, while the A. 

 pharyngea ascendens arises from the systemic arch. Nevertheless its 

 origin is very close to the point where the ductus Botalli from the 

 pulmonary enters the systemic arch. In the Frog there is no con- 

 nexion between the pulmonary and systemic arches in the adult, but 

 there is in the larva. In view of these facts, therefore, and bearing in 

 mind that small cutaneous branches do actually arise from the ductus 



