214 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



Schizonemertini (such as Cerebratulus) the transverse 

 furrow of the Palseonemertine gives place to a deep 

 longitudinal slit, which penetrates the muscular tissue 



Fig. 92. Diagrams of the Eespiratory Ciliated Ducts of (A) Carinella 

 annulata; (B) C. inexpectata ; (c) Polia curta ; (D) Cerebratulvs. 

 (After Hubrecht.) 



of the head, and is continued below into the ciliated 

 canal which penetrates the lobe of the brain (Fig. 

 92 ; D). The respiratory function of these slits has 

 been pointed out by Hubrecht, who has made experi- 

 ments in demonstration of his hypothesis, and who 



