PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 201 



Figure S9.—Pyura curvigona Tokioka: a, 5 mm. individual; b, left half of mantle body, 

 inner side; c, right half of same; d, ciliated groove. 



translucent in other parts of body. Musculature fairly well developed, 

 reddi.sh salmon ; consists of about 20 longitudinal muscles converging 

 at branchial siphon, about V2 converging at atrial siphon and trans- 

 verse muscles surrounding base of respective siphons. Branchial 

 siphon subterminal, reddish; atrial short, situated near middle of 

 body, both apertures 4-lobed. 



Branchial sac reddish orange, with six folds on each side. Inner 

 longitudinal vessels arranged (D = dorsal, V== ventral) : 



20 mm. lonfi individual 

 (11) 3 (10) 4 (11) 3 (IK) 4 (l.^>) 4 (10) 5 V 

 (1.5) 4 (12) 4 (1(1) 4 (10) ?> (14) .5 (13) 4 V 

 .") mm. long; Individual 

 (7) 1 (S) 1 (10) 2 (10) 2 (0) 2 (0) 1 V 



Transverse vessels arranged: thick thin luediiim (bin (hick, every in- 

 terval intervened by pai'ast igniatic vessels. Jn smallest specimen, how- 

 ever, thicker and tliiiiner vessels alternate rather regularly, para- 



Left 

 Right 



Riglit 



IJ 1 



