No. 2.] EMBRYOLOGY OF THE LIZARD. 361 



tended investigations of this part might throw Hght on the nature 

 of the notochord. Shipley has recently described in Petromyzon 

 the anterior end of the notochord as " being in contact with the 

 posterior end of the nasal invagination." Hiibrecht^ has inge- 

 niously suggested the derivation of the notochord from the pro- 

 boscidean sheath of nemertines. If this view be accepted, the 

 connection of the notochord and hypophysial invagination would 

 apparently add weight to it, especially since Hcape^ has shown 

 that at one period the notochord is tubular in the mole, and 

 that its anterior end is also at first fused with the epiblast 



In conclusion, I wish to add, as apology for having entered the 

 field of speculation, that in so doing my desire has been simply 

 to call attention to points that seem worthy of future investi- 

 gation. 



1 HubrecJit. — On the Ancestral Form of the Chordata. — Quart. Joztr. of Mic. 

 Sci., Vol. XXIII., N. S. 1883. 



^ Heape.—'Y\i& Development of the Mole (Talpa Europea).— Quart. Jottr. of 

 Mic. Sci., Vol. XXIII., N. S. 1883. 



