200 THE SALAMANDER 



passes, and consequently may sometimes be overlooked. It can only 



be regarded as forming a portion of the inferior orbital artery. 



In this connexion it is interesting to compare the relations found 

 in the human embryo and in Sphenodon (see O'Donoghue, 1921, 

 p. 192). In the human embryo the inferior orbital artery is given off 

 from the mandibular branch of the stapedial artery, while in Spheno- 

 don it is one of the two end branches of the A. temporalis. In Sala- 

 mandra both these conditions are present in the one individual. 



The mandibular artery proper continues ventro-laterally through 

 the levator mandibulae muscle close to the nerve, and, like the nerve 

 itself, divides on reaching the lower jaw into a R. lahialis (Osawa) 

 (a.lab.), to the skin on the lateral aspect of the posterior portion of 

 the lower jaw, and ai^. aheolaris (Osawa) (a.alv.), which passes through 

 the inferior dental canal within the jaw itself to supply the teeth, &c. 



In addition to the two main branches just described the A. petrosa 

 lateralis gives one or two RR. musculares to the several portions of 

 the M. levator mandibulae. 



Abnormalities. Two rather interesting anomalies have been met 

 with in this region, viz : 



(i) A case in which the A. petrosa lateralis occurred as a branch 

 of the A. pharyngea ascendens instead of the internal carotid, the 

 latter vessel giving off no branch at all before entering the cranial 

 cavity. The specimen was well injected, and the relations were quite 

 distinct, while the branches of the A. petrosa lateralis were normal 

 and both sides of the specimen were alike. 



(2) A case in which a branch from the A. petrosa lateralis was 

 given off almost immediately after its origin from the internal carotid 

 to the lateral pharyngeal wall. This is the only trace that has been 

 found of a pharyngeal artery stated by Bethge to occur as a normal 

 branch of the internal carotid. Unfortunately the specimen was not 

 injected, and the vessel was nearly empty of blood, so that its exact 

 extent and relations could not be determined (see Fig. 58). 



As already described the internal carotid artery terminates within 

 the orbit as the A. ophthalmica (a.oph.). After leaving the cranial 

 cavity by the oculomotor foramen the ophthalmic artery passes along 

 the optic peduncle, and a short distance from the bulbus oculi divides 

 into four or five branches. It sends two or three branches to the eye 

 itself, and a reflex muscular branch into the MM. retractor bulbi and 

 rectus posterior. The main portion of the artery turns dorsalwards 

 and divides into three vessels : 



(i) R. muscularis^ which curls around the anterior aspect of the 



