PHYLUM CHORDATA 



11 



drawn out into a sort of stalk on which the buds are developed 

 (Fig. 712). A pair of ovaries (ov.) lie in the trunk-cavity, and 

 there is a pair of oviducts (ord.) (originally supposed to be eyes) 

 lined by elongated, pigmented epithelium. The development, 



CephalOdisCUS. Enthi; zooid. (Aftur Mfliitnsli.) 



which is direct, without free-swimming larval stage, takes place 

 in passages in the investment. According to one account the 

 segruentatidii is complete, but unequal and a gastrula is formed 

 by invagination: aceoi'ding to anothei', the segmentation is in- 

 conijjlete, and a gastrula is formed by delamiuation. 



