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 a.gl 



at.tn 



FIG. 29. Individual of the sexual generation of the Salpian Doliolum tritonis 

 X 10. at, atrial aperture; atl, atrial lobes; atm, wall of atrium; br, branchial or 

 oral aperture; brl, branchial lobes or tentacles; brs, branchial sac or pharynx; 

 dt, dorsal tubercle; end, endostyle; h, heart; m, mantle; mi-m 8 , 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 (blastozooids) 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, trophpzooid 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; Ib, lateral buds; mb, median buds; ng, nerve 

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

 after Uljanin and Barrois.) 



