2o6 THE SALAMANDER 



ventral to the base of the skull in the region of the occiput, that is 

 some seven millimetres or so anterior to the origin of the subclavian 

 arteries, and a very considerable distance before the mesenteric 

 vessels are given off. The fusion of the aortic arches in the Sala- 

 mander is thus much more complete than in the Frog and there 

 is no question of any asymmetrical origin of the coeliaco-mesenteric 

 vessels. 



Branches of the Dorsal Aorta 



(PI. XIV, fig. 6i ; and PL XVII, figs. 64 and 64a) 



These may be arranged in three groups according to their distri- 

 bution, as follows: 



Group I. Vessels of the Alimentary Canal (all of which leave 

 the aorta in the mid-ventral line). 



(i) AA. gastricae anteriores (a.g.a.) (Hyrtl, Osawa, Bethge). One or 

 two small vessels arising at about the level of the subclavian arteries, 

 and passing obliquely backwards through the mesentery to their 

 distribution over the dorsal wall of the stomach. 



(ii) A coeliaco-mesenteric complex^ comprising one large vessel, 

 which may be called the coeliaco-mesenteric artery, and a series of 

 smaller ones arranged in 'anterior' and 'posterior' bundles. 



The coeliaco-mesenteric artery (arteria intestinalis, Hochstetter) is 

 a very large vessel almost equal to the diameter of that from which 

 it springs. It arises at about the level of the tenth vertebra and oppo- 

 site the posterior end of the stomach, immediately posterior to the 

 junction of the post-caval and post-cardinal veins, and then passes 

 ventrally through the mesentery to supply the stomach, spleen, pan- 

 creas, liver, duodenum, and the anterior section of the intestine, by 

 means of the following four branches. 



{a) A. gastrico-lienalis (a. g. lien.) or A. gastrica posterior (Hyrtl, 

 Osawa) which, as its name implies, is distributed to the spleen and 

 stomach. Its course runs anteriorly through the mesentery separat- 

 ing these two organs, more or less parallel with the vein of the same 

 name, but nearer the stomach than the latter vessel. It supplies the 

 dorsal stomach wall only, by means of a series of branches arising at 

 intervals of about a millimetre along its length, and approximately 

 at right angles to it. The spleen is supplied by a similar series of 

 branches arising from the opposite side of the vessel. 



(^) The A. duodeno-hepatica (a.d-h.) or A. mesenterica prima (Hyrtl, 

 Osawa) which passes ventrally through the distal edge of the pan- 

 creas alongside the portal vein. Very soon after its origin one or two 



