ADULT HEAD KIDNEY OF BDELLOSTOMA STOXTTI 853 
Fig. 1 Head kidney showing the division into lobes. The nephrostomes which 
lie close together over the surface could not be represented with the magnifi- 
cation used. 
Fig. 2 Transverse section through the head kidney, passing through two lobes ; 
in the one on the right the tubules are cut for the most part longitudinally, while 
in the one on the left they are cut for the most part transversely, v, venous di- 
verticulum with which the head kidney is connected; d, central duct containing 
blood corpuscles and showing connection with both the tubules and the venous 
diverticulum. A few sections both in front of this and back of it the duct forms a 
complete ring lying freely in the venous diverticulum, neph., nephrostomes; 
sin., sinusoids. 
