154 BULLETIN" 100, UNITED STATES NATIONAL MUSEUM. 



larly shaped colonies measure as much as 50 to 60 mm. in di- 

 ameter at the base in one direction and may attain a maximum thick- 

 ness perpendicular to the base of about 30 mm. in the part where the 

 common cloacal aperture is situated. When young the colonies are 

 comparatively thin and flattened. 



Zooids of moderate size, the individual figured (fig. 106), which was 

 moderately well expanded, measured about 1.5 mm. long in the pre- 

 served condition. The body is strongly constricted between the 

 thorax and abdomen, but a muscular process extending out into the 

 test is apparently not developed, perhaps because, owing to the ex- 

 tensive development of the common cloacal canals, the test is much 

 reduced in amount in that layer of the colony where the zooids are 

 situated, most of the zooids being only separated from the adjacent 

 canals by a thin septum of test substance. Branchial aperture with 

 six small lobes; atrial aperture with a thin margin which invariably 

 becomes torn in dissecting out the zooids, so that its shape is difficult 

 to determine, but a careful examination of many zooids failed to dis- 

 close the existence of any atrial languet. 



Mantle musculature very slight. 



Tentacles of three orders regularly arranged. 



Dorsal languets arising from the transverse vessels of the left side, 

 but rather near the median dorsal vessel. 



Stigmata in four rows; the number in a row on each side in several 

 fully developed zooids was found to be as follows: 



Row 12 3 4 



Number of stigmata . 11 11 10 or 11 8 or 9 



No peculiarities were noted in the digestive or reproductive organs 

 except that the testes appeared in some specimens to be partially 

 divided by obscurely indicated radial clefts or furrows into four 

 lobes. In most of the zooids the proximal part of the sperm duct 

 makes many spiral turns (6 to 8) about the testis. 



If the number of localities, as well as the quantity of material 

 collected at many of them can be taken as a safe indication, this is 

 the most abundant and generally distributed ascidian in the Philip- 

 pine region. It was obtained at the stations and places listed below, 

 and in addition there is one lot (No. 156) (Cat. No. 5982, U.S.N.M.) 

 not labeled with a locality. It grows on coral, shells, eel grass, other 

 ascidians, etc., in shallow water. 



No. 97. Station D5218 (off Anima Sola Island, Apr. 22, 1908, 20 fathoms, 



coarse sand.) One very small colony. 

 No. 120. Ulugan Bay, Palawan, December 29, 1908. Two large colonies 



(Cat. No. 59S1, U.S.N.M.). 

 No. G6. Surigao, Mindanao, May 8, 1908. One large colony (Cat. No. 5889, 



U.S.N.M.). 



