140 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



Remarks. — The present specimen conforms well to Ascidia sydnei- 

 ensis samea from Japanese waters in details of the structure of the 

 branchial sac, although the existence of vessels connecting some of the 

 widely interrupted transverse muscles on the right side seems to be 

 unique for the Philippine specimen. The structure and arrangement 

 of the alimentary organs in the present specimen closely resemble the 

 specimens from the Philippine waters of Ascidia depressiuscula Heller 

 which were described by Van Name. The arrangement of the mantle 

 musculature and the appearance of the ciliated groove, however, dif- 

 fer distinctly between the present specimen and Van Name's speci- 

 mens of A. depress kiscula. 



65. Ascidia gemmata Sluiter 



Figure 51 



Ascidia gemmata Sluiter, 1895, p. 177, pi. 9, figs. 7-9.— Sluiter, 1904, p. 29.- 

 Hartmeyer, 1919, p. 95, fig. 19 ; pi. 2, fig. 49.— Tokioka, 1950, p. 131, fig. 11 ; 

 pi. 9, fig. 2.— Tokioka, 1952, p. 103, fig. 9. 



MATERIAL EXAMINED 



Marianas Islands: Saipan, Tanapag Harbor; P. E. Cloud, sta. D-7. One 

 specimen (USNM 11502). 



Caroline Islands: Kapingamarangi Atoll; lagoon reef Hare, in Pocillopora; 

 Cadet Hand, Sta. 333, July 20, 1954. One specimen (USNM 11768). 



Wake Island: C. H. Edmondson, sta. 606. Three specimens (USNM 11754). 



Descriptton. — Five specimens are in the material : three 10-29 mm. 

 individuals from Wake Island, a 30 mm. long individual from Hare, 

 Kapingamarangi, and a small 14 mm. long specimen from Saipan 

 Island. The animals attach to the substratum by the left side. 



Branchial aperture terminal; atrial aperture usually situated ap- 

 proximately at level of posterior one-third of body (fig. 51a). How- 

 ever, on specimen from Saipan which is strongly contracted in anterior 

 half of body (figs. 51b, c) , 9-lobed atrial aperture opens near middle of 

 body. Test gelatinous, translucent or transparent, faintly milky white ; 

 consistency varies from soft to hard ; comparatively thick, smooth on 

 surface. Mantle of moderate thickness, musculature on right side 

 where transverse muscles are rather dominant. Many yellowish cor- 

 puscles in anterior half of mantle body in some specimens, which may 

 indicate that this portion might be reddish in living animals. 



In 14 mm. long individual about 80 transverse vessels, all nearly of 

 same thickness, plications hardly observable. About 40 inner longi- 

 tudinal vessels on right anterior half of sac. Usually 2 (rarely 3) 

 stigmata in a mesh, intermediate papillae absent. Dorsal lamina sup- 

 ported by many ribs, the tips protrude from free margin of lamina. 

 Specimen 30 mm. long has 42 inner longitudinal vessels, its ciliated 

 groove simple, U-shaped (fig. 51<7). Ciliated groove in other speci- 

 mens divided into 2 to 6 sections (figs. 51 c, /). Anterior margin of 

 intestinal loop reaches middle of distance between bases of both 



