ASCIDIANS OF THE PHILIPPINES — VAN NAME. 



145 



Test in the heads more or less transparent, free from pigment in 

 some specimens; in others there is more or less greenish and brown- 

 ish pigment in rounded cells, these occurring also in the mantles of 

 the zooids. In some of the colonies most of the zoo ids have four 

 small dark spots on the anterior part of the thorax. In the pedicels 

 the test is tougher and less transparent, but free from pigment 

 cells. 



Zooids very variable in size, not only in different specimens and in 

 different states of contraction but also in different 

 parts of the same colony. Some of them are 14 

 mm. or more long in the preserved and only 

 moderately expanded condition, but in small, and 

 especially in immature colonies they are all much 

 smaller, not exceeding one-third or one-half this 

 length. A constricted neck of moderate length 

 separates the abdomen from the large and con- 

 siderably elongated thorax, and a large vascular 

 process extends from the posterior end of the 

 abdomen. The vascular processes of the zooids 

 form an anastomosing network in the pedicel. 

 The buds appear to form from the extreme upper 

 branches of this network. Anterior end of the 

 body obliquely truncated so that the dorsal side 

 of the thorax is longer than the ventral side; the 

 anterodorsal region is produced into a large atrial 

 siphon of variable length bearing the small round 

 atrial aperture close to or at its end. The 

 branchial aperture is situated on the oblique an- 

 terior end of the thorax and is scarcely at all 

 prominent, but is of larger diameter than the 

 atrial. Neither aperture lobed. When the zooids 

 are in position in the colony the atrial siphon of 

 each zooid extends above the general surface of 

 the colony toward the apex of the latter. 



Mantle thin, provided with many narrow rather 

 regularly spaced transverse muscle bands in the 

 thorax. These bands are generally quite con- 

 spicuous. 



Tentacles numerous, of 3 sizes. The largest and medium sized 

 ones alternate in one circle; the numerous small ones form another 

 circle nearer the branchial aperture. 



Dorsal languets triangular, continuous laterally with rather broad 

 membranes which are borne on the transverse vessels of the branchial 

 sac. The languets arise directly from the medium dorsal vessel. 

 101825°— Bull. 100—17 10 



Fig. 96. — Nephtiihib 

 thompson! (hebd- 

 m a n). Zooid 

 X 25. 



