136 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



type specimen. Evidently, the number of transverse body muscles 

 is somewhat variable and the longitudinal plications on the stomach 

 may be rather faint in some specimens. 



The present species superficially resembles Pterygascidia mirabUis 

 Sluiter, 1904, from the Siboga area. At first, I considered the present 

 specimens as the second species of the genus Pterygascidia^ although 

 there are the following differences: Pterygascidia has (1) a pair of 

 remarkable fin-shaped semicircular prominences on the dorsal side 

 just behind the atrial aperture; (2) an oblique row of short muscular 

 pieces on each side of the anterior half of the body; (3) no real stig- 

 mata on the branchial sac; (4) esophagus considerably long, proceeds 

 forward at first, turns backward to the posterior end of the body and 

 then runs anteriorly again to the stomach; and (5) dorsal lamina a 

 plainly edged membrane. The third difference is somewhat impor- 

 tant, but Sluiter's figure (pi. 7, fig. 2) seems to show an intermediate 

 state between the stigmatal structure and the strictly nonstigmatal 

 one. For this reason this point cannot be accepted as an essential 

 generic characteristic differentiating the present specimens from 

 Pterygascidia. The differences 1, 2, and 4 can be of specific impor- 

 tance, but they cannot be accepted as generic characteristics. How- 

 ever, the last difference is considered as a very important generic 

 characteristic, and hence I want to retain Van Name's genus Gialhisia 

 for the present specimens. 



Family Perophoridae 



61. Perophora formosana (Oka) 



Ecteinascidia formosana Oka, 1931a, p. 173, 3 figs. 

 Perophora beT^nudcnsis Berrill, 1932, p. 80, fig. 3A. 

 Perophora orlcntalis AmbJick-Christie-Linde, 1935, p. 6. 1 fig. 

 Perophora formosana Tokioka, 1953a, p. 218, fig. 9 ; pi. 31, figs. 4-5. 



MATERIAL EXAMINED 

 Palau Island : Iwayama Bay, east side of Oyster Pass ; GVF sta. 220. One 

 zooid (USNM 11441). 



Wake Island: C. H. Edmondson, sta. G13. One large colony (USNM 11756). 



Description. — A single individual from the Palau Islands and a 

 large colony consisting of a number of zooids from Wake Island were 

 examined. The specimen from the Palau Islands is a zooid 2 mm. 

 long, its test and mantle are transparent and a small amount of pur- 

 plish-brown pigments are contained between the stigmata which are 

 arranged in five rows, but a few of them extend to both the first and 

 the second rows. In the specimens from Wake Island, the mantle 

 musculature passes through both anterior and posterior sides of the 

 atrial aperture. Each stigmatal row contains 20-25 stigmata. 



