PACIFIC TUNICATA OF U.S. N \TIONAL MUSEUM 195 



izuana, occupying the whole ventral half of the left side, it is confined 

 to the posteroventral part of the left side in the present specimens ; (2) 

 the stomach lias many more, up to 40, longitudinal plications, but with- 

 out any distinct pyloric caecum in jS. izuana; (3) the lobation of the 

 anal margin is more remarkable in the present specimens than in S. 

 izucma, in which only four lobes are defined; (4) testicular follicles 

 are found along nearly the whole lateral sides of the gonad in >S'. 

 izuana; (5) the ciliated groove is U-shaped in ^S'. Izuana. At present, 

 however, it seems that these differences camiot be accepted as being of 

 the specific importance to separate these specimens from S. izuana. 

 Rather, I prefer to treat the present specimens as a subspecies of S. 

 'izuatui. 



101. Styela coriacea (Alder & Hancock) 



Figure 85 



Cynthia coriacea Alder & Hancock, 1848, p. 195. 



Styela coriacea Hartmeyer, 1923. p. 220 (synonymy). — Van Name, 1945, p. 285, 



fig.s. 179F, 181-183 (synonymy). 

 Styela plata Oka, 1930, p. 427, tigs. A-C. 



MATERIALS EXAMINED 



Japax : Hokkaido Island; Otaru. E. S. Morse, coll. Specimens, 27 

 (USNM 11688). 



Descrii^tion. — Examined were 27 specimens from Hokkaido Is- 

 land, Japan. All are low, conical in shape, with a very wide mem- 

 branous marginal prolongation of test around base of animal, and at- 

 tached to the substratmn by whole wide underside. Largest of the 

 specimens is 25 mm. X 21 mm. in extent and 7-9 mm. in height. 

 Branchial aperture subterminal and atrial situated near it, both aper- 

 tures 4-lobed and nearly sessile. Test thin, leathery and pale yellowish ; 

 basal marginal portion of test densely encrusted with fine black sand 

 grains which gradually decrease density towards animal body proper. 

 Thus dorsal siphonal region always exposed. Surface wrinkled irreg- 

 ularly by contraction. Mantle delicate, especially in ventral half; 

 yellowish brown. 



Inner longitudinal vessels of branchial sac arranged (D = dorsal, 

 V= ventral) : 



Left D (10) 2 (5) 2 (10) 2 (8) 1 V 



Right D (11) 2 (7) 1 (10) 2 (8) 1 V 



Transverse vessels and parastigmatic vessels alternate regularly; some- 

 times thinner parastigmatic vessels of second order may be found in 

 intervals between transverse vessels and usual parastigmatic ve.sse]s 

 of first order. In each mesh 7 to 10 very elongated stigmata, may be 

 up to 20 in larger meshes along endostyle. Tentacles 25-30; edge 

 of dorsal lamina plain. iVxis of second intestinal loop passes through 

 esophageal region. Stomach elongated, longer than half of ventral 



