NO. 1368. 



DESaUPTIOXS OF AUG I'LIDJ:— WILSON. 



633 



of the usual shape, but has only five openings instead of six. the 

 ventral one consistino- of a single lonoitudinal slit. 



All the blood enters through the lateral valved openings {(i)\ a part 

 of it passes out of the aorta {h) anteriorly and another part out of the 



Y-[r,. 9. — Thk nervot'p system of AKnri.rs amf.ruaxvs. 



posterior median aperture {d)\ each of these streams follows the usual 

 course (fig. 8), but the greater bulk turns downward and passes out of 

 the ventral median slit {c). 



