ARTERIES OF MAMMALIA. 



545 



423 



A closer resemblance to 

 the plexiform limb-arteries 

 of the Sloths is shown by 

 the Slow Lemurs, as exem- 

 plified in the arm of Stenops 

 tardigradus in fig. 423, c. ] 



Cuvier first indicated the 

 analogous division into nu- 

 merous branches of the 

 brachial artery of the Por- 

 poise; 2 the plexuses after- 

 wards receiving a more 

 detailed account, with a 

 figure, from V. Baer, 3 who 

 also found a similar ar- 

 rangement in the pectoral 

 fin of the Manatee, 4 and, 

 with a minor degree of 

 subdivision, in that of the 

 Walrus. 5 V. Baer associ- 

 ates the speedy subdivision 

 of the main artery with the 

 restricted degree of move- 

 ment of fin-shaped fore- 

 limbs : but the extent and 

 freedom of motion of the 

 long prehensile limbs of the 

 Sloths and Lemurs point to 

 other conditions. 



The extreme degree of 

 plexiform multiplication of 

 the arterial system in the 

 intercostal and other ver- 

 tebral branches, in the Ce- 

 tacea, more plainly relates 



1 Vrolik remarks of these plex- 

 uses, ' they consist not only of ar- 

 teries, but also of veins ; and that, by 

 dividing in branches, these ramifi- 

 cations become smaller and smaller, 

 and composed of a less number of 

 vessels.' lxix\ p. 219. 



2 xii. (1805, torn. 4). 



3 CXCVl". fig. I. 



4 lb. fig. n. 



3 lb. fig. in. 

 VOL. III. 



Plexiform branches of brachial artery; Stenops tardigradus. 



I.XLX'. 



N X 



