PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 67 



Thorax 430 to 560/x long in spechnons examined. Ketractile muscle 

 of moderate length, or attaining iy^ times the length of contracted 

 thorax. Usually a fan-shaped thoracic organ is found near postero- 

 ventral corner of the wide atrial aperture on each side. Branchial 

 aperture G-lobed, artial languet absent. Stigmatal rows 4; about 6 

 stigmata in each row. One testicular follicle, proximal part of vas 

 deferens coiling 4-7 times. Intestine not cui^ved strongly in zooids 

 with immature gonads. 



Trunk 550/a long m a larval specimen examined. Three attacliment 

 processes arranged lineally, four pairs of ampullae present. 



20a. Didentnum (Didemnum) moseleyi forma granulatum Tokioka 



FiGUBES 20e,f 



Didemnum (Didemnum) moseleyi f. granulatum Tokioka, 19o4a, p. 6, pi. 21, 

 figs. 1-4. 



MATERIAL EXAMINED 



Palau Islands : Barrier reef 8 mi. NW. of Koror Islaud ; GVF sta. 25. Many 

 colonies (USNM 113S0). — Iwayama Bay, east side of Oyster Pass; GVF sta. 

 220. Several colonies (USNM 11412) . 



Description". — Many small colonies attached to a solitaiy ascidian 

 {Polycarpa iwayamae Tokioka), and to colonies of an alcyonarian 

 coral. The larger specimens examined are 19 mm. X 7 mm. or 12 mm. X 

 10 mm. in extent and 0.5 mm.-l mm. in thickness; they are whitish in 

 color. 



Spicules of moderate size, 22-28/a in diameter in colonies from GVF 

 sta. 220 and 27-31/i in those from sta. 25, and distributed densely and 

 evenly throughout test from bottom to surface; rays are rather slender, 

 7 to 9 on the equatorial plane. Superficial spiculeless layer indiscern- 

 ible; small granular prominences formed by aggregated spicules on 

 entire surface of colony, especially densely aromid branchial aper- 

 tures and above lacunar systems. Common cloacal apertures some- 

 times supported by about 20 riblike structures made of spicules, as 

 seen in specunens from GVF sta. 220 of the Palau Islands (fig. 20e). 

 Thoracic lacunae distinct and spacious. Zooids rather small; atrial 

 apertures wide ; G stigmata in each of 4 rows. One testicular follicle, 

 proximal part of vas deferens coiling 5-7 times. 



Larvae small, with 4 pairs of ampullae, two pigment flecks of sen- 

 sory organ arranged anteroposteriorly. 



21. Didemnum (Didemnum) nekozita, new species 



Figure 21 



HoLOTYPE.— USNM 11381 ; Palau Islands : barrier reef 8 mi. NW. 

 of Koror Island 7°24'30" N., 134°21'20" E. (HO chart 6102, 1st 

 ed.) ; 3-7 feet, sand, coral heads, and dead coral; GVF sta. 25, July 19, 

 1955. 



