P.S. 



D 



C.M. 



Fie. 1. I 



ini'iix cin-i-iii/iiiiig. -Continuation 

 Mack). CM., circular muscle- 



|l|-(ll)IIScis slieatll. 



Int 



it' (lie scries uf diagrams illustrating the vascular- system (solid 

 ; Int., intestine: M., inrmtli ; Oes., oesophagus; P.S., cavity of 



A Bridges (if connective tissue and muscles be^in to cross the blood-space irregularly, breaking it up into a network 

 of intercommunicating vessels. A ,mall blood-vessel, with very thin dorsal wall, is now appearing in the wall 

 of the proboscis-client b, mi the vent nil side. (The proboscis is no longer seen, having been torn out in this 

 specimen.) 



B A median ventral blood-space has appeared temporarily, but is already being encroached upon by the connective 

 tissue, and separated into two lateral spaces. 



C The branch,-. <>| the blood-- pace are becoming widely M-parated, and spreading round to embrace the walls of the 

 oesophagus and mouth, which have nou appeared. 



D The final condition of the blood-space with its network of vessels. These now lie below the inner layer of 

 longitudinal muscles, and cuiiiplctch surround the intestine. The blood-vessel of the proboscis-sheath is 

 still seen, its dor-al wall being an exceedingly thin membrane (exaggerated in thickness in the drawin-jl. 



