ASCIDIANS OF THE PHILIPPINES — VAN NAME. 



77 



Apertures (both 4 lobed) wide apart on dorsal side, the branchial 

 generally the most prominent, though in the contracted preserved 

 specimen neither aperture may project much. As would be expected, 

 there is in the considerable series of specimens collected much varia- 

 tion in external characters. Test moderately thick, of an opaque 

 white color; tough and leathery in alcoholic specimens, but softer 

 and more translucent in formalin specimens. Outer surface uneven, 

 with wrinkles and irregular depressions and elevations, yet in places 

 moderately smooth, and only occasionally much incrusted with 

 foreign matter. Inner surface of test white and glistening. The 



I'igs. 19-25. — Pyura pallida (Heller). 19, Left and right sides of body. X .75. 

 20, Spicules. The long ones are from the mantle, the shout ones from the 

 test. X 15. 21, Part of a spicule. X 225. 22, Tentacle. X 15. 23, Dorsal 

 tubercle and part of dorsal lamina of two individuals. X 9. 24, Hepatic 

 tubules. X 20. 25, Part of gonad. X 4. 



dorso-ventral diameter may be less than, or may exceed, the length. 

 Size of one of the largest specimens : Length, 45 mm. ; dorso-ventral 

 (inclusive of elevation bearing branchial orifice), 52 mm.; lateral 

 diameter, about 15 mm. Apertures nearly 30 mm. apart. 



Tissues of the mantle (and to a less extent those of some of the 

 other internal structures of the body) containing slender, slightly 

 curved needlelike calcareous spicules, which taper toward one or both 

 ends. They are densely covered with minute appressed spines ar- 

 ranged in rings (fig. 21). All the spines point toward one end of the 

 spicules; this end is not so sharp as the other. The spicules are 

 mostly between 0.75 mm. and 2 mm. in length, but larger and smaller 

 ones also occur. Similar, but much smaller, and proportionately 



