1905 ] ANATOMY OF THE FERRET-BADGER. 29 



arteries and afterwards divide into right and left halves. The 

 first pair of intercostals corresponds to the fii'st branch of the 

 Azygos *. The first six pairs of intercostals lie entii-ely to the 

 left of the Azygos ; the 7th artery on the right side and those 

 which follow lie to the right side of the Azygos. This point, I 

 take it, is where originally the now missing right aortic arch 

 joined the left aortic arch. In this region the aorta also gives 

 ofi" a number of fine slender branches to the oesophagus and to 

 the lungs. The first of these branches arises a little way down 

 the first right intercostal and suj^plies the windpipe ; from or in 

 the immediate neighbourhood of the next four light intercostals 

 arise twigs for cesophagus and lungs ; then follows a gap of two 

 intercostals, the last twigs arising from the 8th right intercostal. 

 From the last intercostal in front of the diaphragm arises a 

 diaphragmatic artery on each side ; another diajjhragmatic artery 

 springs directly from the aoi-ta behind the diai^hragm, and 

 independently of an immediately following sujDrarenal artery. 



I have carefully and, I hope, exactly compared the pre- 

 diaphragmatic artei-ies of Helictis with those of its ally Gcdictis 

 and with those of the ^luroid Suriccda. 



The former, as might be expected, shows greater resemblances to 

 Helictis than does the latter. There are, however, also difl:ei'ences. 

 There are 1 instead of 1 1 pairs of intercostals in front of the 

 diaphragm, or, to be more absolutely accurate, 10 on one side and 

 9 on the other ; for the first intercostal has not a fellow and 

 belongs to the left side. The fifth right intercostal is the first 

 which passes to the outside of the Azygos vein. The pulmonary 

 and cBsophageal branches arise in every case from the right 

 intercostal vessels, and I counted four of them which have the 

 following position : the first three aiise from the first three 

 right intercostals ; the fourth sj)rings from the fifth right 

 intercostal. 



In Suricata tetradactyla there are 12 intei^costals on the right 

 side in front of the diaphragm and two additional ones on the 

 left side. The most imjjortant pulmonary and oesophageal arteries 

 arise separately from the aorta, though some spring from right 

 intercostals. The 8th right intercostal is the first which passes 

 over the Azygos vein. 



* This vessel, as in most mammals, is present onlj' on the right side. 



