XIII 



PHYLUM CHORDATA 



33 



and by the tail aborts, and two processes, one postero-dorsal, the 

 other ventral, known respectively as the dorsal (dors, st.) and ventral 



FIG. 691. Diagram of the metamorphosis of the freetailed larva into the fixed Ascidian. A, stage 

 of free-swimming larva ; B, larva recently fixed ; C, older fixed stage, adh. adhesive papillae ; 

 atr. atrial cavity ; cil. gr. ciliated groove'; end. endostyle ; lit. heart ; med. ganglion of trunk ;. 

 n. gn. nerve-ganglion ; noto. notochord ; or. oral aperture ; rect. rectum ; sens. ves. sense 

 vesicle ; stig. stigmata ; stol. stolon ; t. tail. (From Korschelt and Heider, after Seeliger.) 



stolons (vent. St.), grow out from the body of the larva. On the 

 latter are formed a number of slight projections or buds. These 

 VOL. II D 



