xm 



PHYLUM CHORDATA 



319 



behind, closely applied together. Each is prolonged anteriorly 

 into the corresponding olfactory peduncle or tract, somewhat dilated 

 in front to form the olfactory bulb (olf.) from which the olfactory 

 nerve arises. In the interior of each is a cavity, the lateral 

 ventricle or paracoele, sending a prolongation forwards into the 



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olfactory bulb, and communicating behind by a small aperture, the 

 foramen of Monro (D, f. m.), with the diaccele (v. 3). Through the 

 foramen of Monro there passes into each paraccele a vascular 

 process of pia mater, the choroid plexus (ch. p.) : immediately above 

 and behind this is a hippocampal commissure (c.p.a.) connecting 

 together two areas known as hippocampi, one on the mesial surface 



