1026 



MR. L. R. CRAWSHAY OX THE ARTERIAL [Dec. 11, 



howevei', dissociating these two latter bi'anches from any common 

 origin, it is perhaps more desirable that I should hei'e i-ef'er to 

 them merely as the r. abdominis externus and r. ahdominis i:i'e)-niis 

 respectively. 



Text-fio-. 151. 



Bufo boreas, ? (X If). 

 Ventral view of Aa. uroffenifales, &c. 



(For explanation of the lettering, see p. 1033.) 



In E. escidenta, B. cateshiana, R. clamata, B. horeas, and 

 B. mauritanicus, the first branch to ai'ise was the r. ahdominis 

 extermis, running down to the extreme base of the M. rectus 

 ahdominis, from which as a conspicuous vessel the A. vesicalis 

 ventralis Avent in R. cateshiana to the allantoic bladder. In these 

 cases, then followed the A. 7-ecto-vesicalis, its distribution being 

 mainly or entirely to the bladder. 



In R. tigrina and R. hexadactyla, on the other hand, the recto- 

 vesicalis was given off before the r. abdominis externus, while in 

 the latter species a small artery ran back first of all to the 

 M. coccygeo-iliacus which was not observed in the others. 



