PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 69 



Philippine Islands : Baliwasan ; W. R. Taylor, sta. 10, eight small 

 colonies (USmi 11798). 



Description. — Many small colonies from the Palau Islands and 

 several small ones from the Philippines. Larger colonies are 8 mm. 

 X7 mm., 10 mm. X5 mm., and 14 mm.X4 mm. in extent and 1 mm. in 

 thickness. They are attached to the surface of alcyonarian colonies, 

 the basal portion of colonies of a compound ascidian Synclavella 

 sp., the leaves of Enhalus acoroides (L.f) Steud, and other plants. 



Color, usually whitish, though slightly grayish or yellowish in 

 some colonies, due to existence of many calcareous spicules in test. 

 Generally a single common cloacal aperture opens near center of 

 colony. Test slightly swollen above individual zooids, many small 

 prominences of various shapes (fig. 216-/) scattered on surface; 

 one is situated at ventral side of branchial aperture of each zooid, 

 i.e., the side facing periphery of colony (fig 21a) . Some fecal pellets 

 found embedded under thin sujDcrficial spiculeless layer between 

 zooids. No system found in arrangement of zooids. Thoracic lacunae 

 well developed, hypoabdommal lacunae absent. 



Spicules rather small, 22-27/u, in diameter in measured examples, 

 about 24/x on the average. In most colonies spicules distributed rather 

 densely and evenly throughout test from bottom to surface. Spicules 

 somewhat sparse in the four colonies found attached to the colony 

 of Synclavella collected on the Palau Islands; in such colonies con- 

 sistency of test is rather soft as compared with those densely packed 

 with spicules. Spicules may be nearly of the typical moseleyi-iovra. in 

 some colonies, with rays blunt at the tip and 5 to 8 in number on the 

 equatorial plane; in addition, a small number of spicules consisting 

 of very short and bluntly tipped rays. In many other colonies, how- 

 ever, spicules consist of considerably fewer (8 to 10) and more slender 

 rays, each ending in a blunt tip; thus there are only 4 to 8, most fre- 

 quently 5 to 6, rays on the equatorial plane; also a few giant spicules 

 consisting of about 5 rays. 



Zooids mostly sexually immature. Branchial aperture 6-lobed, 

 atrial languet absent. Retractile muscle of moderate length, often 

 reaching li/^ times the length of contracted thorax. Four stigmatal 

 rows and six to seven stigmata in each row ; dorsal languets distinct. 

 Tentacles about 12, of which the dorsal is longest. Other structures 

 of thorax and abdomen quite the same as those of Didemnum 

 {Didemnum) moseleyi (Herdman) . In some zooids there are a couple 

 of remarkable club-shaped circumintestinal glands on right side of 

 intestinal loop at level of stomach (fig. 21^) ; in some others a certain 

 reddisli brown glandular tissue is found also on right side of in- 

 testinal loop (fig. 21j). One testicular follicle, rarely two; proximal 

 portion of vas deferens coiling about five times. 



