ASCIDIANS OF THE PHILIPPINES VAN NAME. 



117 



Mantle thin, but with numerous muscle fibers disposed singly or 

 in narrow bands or loose groups. On the anterior part of the body 

 the deeper ones are mostly transverse and overlaid with longitudinal 

 ones, these also being separate or only gathered into very narrow 

 bands. The transverse fibers become more widely spaced and less 

 regularly disposed (running in various oblique directions) en the 

 middle and posterior regions of the body, and the musculature prac- 

 tically disappears on the posterior part of the left side. 



In one of the largest specimens about 48 tentacles were counted; 

 the}" are of three orders, not very regularly arranged. 

 Dorsal tubercle simple, its orifice C-shaped, U- 

 shaped, or V-shaped in most specimens, with the open 

 interval forward or to the 

 right and the horns curved 

 inward (rarely outward), but 

 not spirally coiled. Ganglion 

 a considerable distance back 

 from the dorsal tubercle. 



Dorsal lamina with lateral 

 ribs, narrow and plain-edged 

 in the anterior part, wider and 

 provided with small but not 

 very regular slender teeth far- 

 ther back. It passes to the left 

 of the esophageal orifice, be- 

 coming much lower after pass- 

 ing the orifice, though in some 

 specimens it can be traced a 

 considerable distance farther 

 back. Another membrane, also 

 more or less denticulate, arises 

 from the space just anterior to the esophageal orifice and is continued 

 parallel to the dorsal lamina past the orifice on the right side and for 

 some distance back. The papilla? along the right side of the area sur- 

 rounding the esophageal opening (described by Heller, 1878, p. 87), 

 were also observed in the Albatross specimens. They represent the 

 supporting papillae of the most dorsal internal longitudinal vessel 

 of the right side; this vessel is, however, rudimentary or wanting, 

 and the papillae are larger and longer than usual. 



Branchial sac extending far back beyond the mouth of the 

 esophagus. Transverse vessels numerous; in some individuals three 

 or four orders arranged with considerable regularity may be recog- 

 nized on most parts of the sac; in others, though large vessels occur 

 at intervals, the vessels of the smaller orders are in most [daces nearly 



Figs. 72-74. — Phalldsia depressiuscula 

 (Heller). 72, Left side of body. One- 

 half NATURAL SIZE. 73, LEFT SIDE OF BODY 

 OF ANOTHER INDIVIDUAL. X .75. 74, I'AHT 

 OF BRANCHIAL SAC. X 15. 



