THE PHYLUM CHORDATA 



57 



tinct dorsal lamina. The atrium has two wings that extend laterally 

 to receive water from the pharyngeal clefts, and opens broadly on the 



n.g «.Bl n 



."at. I- 



Fig. 29. — Individual of the sexual generation of the Salpian Doliolum trilonis 

 X 10. at, atrial aperture; all, atrial lobes; atm, wall of atrium; 6r, branchial or 

 oral aperture; lyrl, branchial lobes or tentacles; hrs, branchial sac or pharynx; 

 dl, dorsal tubercle; end, endostyle; h, heart; m, mantle; mr^ms, circular muscle 

 bands; n, nerve; ng, nerve ganglion; ov, ovary; pbr, peribranchial or atrial cavity; 

 pp, peripharyngeal bands; sg, stigmata; sgl, subneural gland; so, sense organ; 

 si, stomach; t, test or tunic; tes, testis; z, prebranchial zone. (After Herdman.) 



Fig. 30. — Life history of Doliolum. A, tailed larval stage; B, "nurse" or 

 oozoiod, showing buds (blastozobids) migrating from the ventral stolon to the 

 dorsal process; c, posterior part of much later oozooid to show buds arranged in 

 three rows on the dorsal process; D, stolon segmenting; E, young migrating bud; 

 F, trophpzobid developed from one of the buds of a lateral row. 



At, atrial aperture; b, buds; Br, branchial or oral aperture; cl, cloaca; dp, dorsal 

 process; end, endostyle; ht, heart; lb, lateral buds; mb, median buds; ng, nerve 

 ganglion; ot, otocyst; pc, pericardium; sk, stalk; sto, stolon. (From Herdman, 

 after Uljanin and Barrois.) 



