ASCIDIANS OF THE PHILIPPINES — VAN NAME. 85 



Mantle thin, firmly adherent to the test, its musculature composed 

 chiefly of narrow and widely separated bands. The more conspicu- 

 ous ones cross the dorsal region or radiate from the apertures, extend- 

 ing down on the sides. These are crossed by circular bands and 

 fibers surrounding the apertures, or extending longitudinally on the 

 body. 



Number and arrangement of tentacles very variable. Each indi- 

 vidual studied had one very large tentacle, and several others also 

 large enough to leave no doubt that they should be considered as of 

 the first order. Smaller and less extensively branched tentacles are 

 present in the intervals; but only in a few parts of the circle was 

 any regular arrangement recognizable. The largest tentacles, though 

 of great size in proportion to the body of the animal, are not very 

 complex in their branching, and are not more than three (or to a 

 small extent four) times compound. The branching is quite irregu- 

 lar and the tips of the small branches are blunt and slightly en- 

 larged. The tentacles bear broad membranes. 



Dorsal tubercle small, the form of its orifice difficult to make out 

 in the specimens examined, but apparently very simple, perhaps oval 

 or crescent-shaped. 



Dorsal lamina represented by a series of rather large triangular 

 languets corresponding in number and position to the origins of 

 the transverse vessels. Their broad diameter is transverse to the 

 median dorsal vessel. 



Branchial sac very delicate, the large meshes formed by the trans- 

 verse and internal longitudinal vessels are generally not crossed by 

 any smaller vessels, except that in a few places a small intermediate 

 transverse vessel may extend across one or two successive meshes, 

 rarely more. Only four distinct folds were positively demonstrated 

 on each side; the rudiment of a fifth fold, indicated by two closely 

 placed internal longitudinal vessels, was present on each side in one 

 individual at least. The distribution of internal longitudinal vessels 

 in that specimen was about as follows : 



Left side: dorsal (4) 2 (S) 1 (5) 1 (3) 1 (2) ventral. 

 Right side: dorsal (4) 1 (9) 2 (5) 2 (4) (2) ventral. 



These vessels are spaced so as to form, with the transverse vessels, 

 large square or oblong meshes on the intervals between folds; toward 

 the summits of the folds they become more closely placed. 



Alimentary loop horizontally placed, U-shaped, the dorsal branch 

 (formed by the intestine) being the shorter of the two. Stomach 

 long and narrow, tapering gradually into the intestine, and bearing 

 on its dorsal aspect a row of tufts composed of somewhat branched 

 hepatic tubules. 



Gonads present on both sides of the body ; on the left between the 

 branches of the intestinal loop ; on the right rather far back on the 



