PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 193 



One thicker and tliree thinner transverse vessels alternate regularly; 

 a parastigmatic vessel intervenes in every interval. Stigmata 3 to 5 

 in each mesh, up to 8 in larger meshes along endostyle. Tentacles 27, 

 larger and smaller ones ditferentiated. Ciliated groove simple. Sec- 

 ond intestinal loop distinct, axis passes through cardiac end of el- 

 liptical stomach, which is completely liberated from body wall and 

 has 25 longitudinal plications on surface and a distinct pyloric caecum. 

 Anal margin cut into about 15 lobules. Two gonads on each side, testic- 

 ular follicles confined to area surrounding ventral end of gonad. In 

 the 15 mm. long individual with an unusual peduncular prolongation 

 of the test, an excess short third gonad was found on right side (fig. 

 83^). 



Remarks. — It is evident that the specimens here treated are jS. 

 atlantica, although they show rather unusual shape or appearance. 

 The remarkable decrease of test thickness seems to occur in deep- 

 water forms of various ascidians. 



100. Styela izuana (Oka) 



Molstycla izuana Oka, 1934, p. 292, figs. A-C. 

 Styela izuana Tokioka, 1953a, p. 269, pi. 64, figs. 1-5. 



Styela Izuana hawaiiensis, new subspecies 



FlGITRE S4 



HoLOTYPE. — USNM 11701: Hawaiian Islands; south coast of Oahu, 

 off Diamond Head Light N. 21° E., 6.9 miles; 304-308 fathoms, fine 

 white sand, mud. Albatross sta. 3908, May 5, 1902. 



Parattpes. — USNM 11795: Hawaiian Islands; northeast approach 

 to Pailolo Channel between Maui and Molokai ; off Mokuhooniki Islet 

 S. 61° W., 10.6 miles; 290-286 fathoms, brown mud, fine sand, Glo- 

 higerina. Albatross sta. 4095, July 22, 1902. Nine specimens. 



Description. — -Ten specimens from Hawaiian waters were examined, 

 the largest (holotype) is 16 mm. in length. All are ellipsoidal in 

 shape with hairy processes all over surface, leaving narrow dorsal 

 siphonal area exposed. Hairy processes usually hold some mud or 

 fine sand grains, siphonal area enciiisted w^ith fine sand grains. Test 

 thin, rather soft and translucent. Both apertures 4-lobed, sessile 

 and separated from each otlier by about 5 nun. Mantle thin, pale 

 l)rownish orange on dorsal, but yellowish on venti-al side. Fine ten- 

 tacles along margin of atrial velum. 



Inner longitudinal vessels of branchial sac arranged in 16 mm. long 



individual ( I) = dorsal, V= ventral) : 



Left I) n (20) 3 (14) 5 (21) S (S) 6 V 



Right. I) (IS) 4 (14) -A (25) 7 (14) 7 \ 



Transverse vessels arranged : thick i- thin j' thick, or, tiiick p (bin p thin 



p thill J' thick (p=parastigiiia(ic vessel). Two to four elongated stig- 



