ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



247 



is at present going on freely. The origin of the Pyrosomes may be 

 found in Compound Ascidians, through such forms as Cyathocormus 

 and Ccelocormus. In contrast to Salps, where species are very distinct 



;jC^*^fe^J^S^8)jM<|>it». 



Fyrosoma atlanticum. A diagrammatic figure 

 of a zooid. After Bergliause. 



tu., mouth; d.a.s., dorsal anterior blood sinus; p/i.b., 

 peripharyngeal ijand of cilia ; tj., ganglion ; 5r.6., branchial 

 bars; d.ls., dorso-lateral blood sinus; d.s., dorsal blood 

 sinus; 5.0. , blood-forming organ: stg., stigma; t.s., blood 

 sinus to tunic ; uc.s., visceral sinus ; a'., oesophagus : d.p.s., 

 dorsal posterior blood sinus; s^., stomach ; in<., intestine ; 

 cl.a., cloacal aperture ; g.s., posterior gonadial sinus ; t., 

 testis: o., ovary; b., bud ; h., heart ; s.s., stolon blood sinus; 

 «.Z.s., ventro-lateral blood sinus; e., endostyle ; tJ.s., ven- 

 tral blcod sinua ; v.a.s., ventral anterior blood sinus ; i^h.s., 

 peripharyngeal blood sinus; l.o., luminous organ; tn., 

 tentacle. 



fir i 









^^-■vt ■•'•--.''•' -■=-^.*#' 

 ■ ' " . . . - . - » - ^ : %. . -Ta 



" ■" ■■ -■':': •r^':%m 



-vt 



'^^^Vra 



. - Vi 









Pyrosoma atlanticum, form 



A colony seen from the 

 flattened face, x g. 

 After Brooks. 



