PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 75 



cleared to belong to Didemninn (Didemnum), thus, it is replaced by 

 dorotubu, new name {doro = muddy and tubu=])Q\\et in Japanese). 

 It is very possible that the present species is identical with Hypurgon 

 skeatl Sollas from the jSIalay Peninsula, but at present I have not yet 

 studied enough specimens from various localities to ascertain this 

 identity. 



26. Didemnum (Didemnum) misakiense (Oka & Willey) 



Figures 24&-e 



Sarcodidemnoides misakiense Oka & Willey, 1892, p. 313, pis. 17-18. 

 Didemnum (Didemnum) misakiense Tokioka, 1955c, p. 23. 



MATERIAL EXAMINED 



Japan : Off Omai Zaki Light, Honshu ; Albatross sta. 3727. Oue colony 

 (USNM 11777). 



Philippine Islands : Off Jolo Light ; Albatross sta. 5174. One colony 

 (USNM 11749), attached to gorgonian coral of the genus Ecliinogorgia (USNM 

 52052). 



Description. — Two colonies are in the material. The colony from 

 the Philippine Islands is attached to the middle of a large Echinogorgia 

 (cat. no. 52052), 3.5 mm. in diameter and 250 mm. in length, and it 

 consists of about a dozen mammillary prominences, 70 mm. X 65 mm. 

 X 30 mm. in extent and pale grayish yellow in color; the largest mam- 

 millary process is 23 mm. X 5 mm. in extent and 31 mm. in thiclmess. 

 The colony from Japan is 35 mm. X 25 mm. in extent, pale yellowish 

 brown and consists of only three irregularly shaped mammillary 

 processes. 



Axial core of test is soft, gelatinous, translucent, somewhat paler 

 in color and much less densely impregnated with spicules than the 

 surface layer. Zooids arranged in a single layer, forming the thin 

 zooidal stratum enclosing the axial core. Spicules and also pigment 

 cells found most densely in outer layer of this zooidal stratum. Super- 

 ficial spiculeless layer extremely thin, consequently some parts of 

 colonies are rather rough to the toucli. Well-defined hypozooidal 

 lacunae developed })etween zooidal stratum and axial core. Spicules 

 very small in Japanese specimen and of the nioseleyl-type, but only 

 13-18ju, in diameter and with 8-9 rays on the equatorial plane. Spic- 

 ules somewhat larger in Philippines specimen, 24—33^ in diameter and 

 with 9-13 (about 12 on an average) rays on the equatorial plane. 

 Usually a single roundish common cloacal aperture situated near 

 summit of each mammillary process, although one or two more com- 

 mon cloacal apertures may be seen on some large mammillary proc- 

 esses. Atrial a]:)erture very wide, with a kind of very short and bifid 

 atrial languet ( 'i) (figs. 2-i^d,e) in the Philipi)ine specimen. Stigmatal 

 rows four, one testicular follicle, proximal part of vas deferens coils 

 six to eight times. 



20G-191— 67 6 



