REPORT ON THE TUNICATA. 79 



are slight, with generally three or four internal longitudinal bars upon each (PI. V. fig. 10). 

 Usually there are no bars on the spaces between the folds, but sometimes one may be 

 present. These spaces are, however, traversed by narrow membranes, horizontal, oblique, 

 and longitudinal — the horizontal ones (PI. V. fig. 10, h.m.) indicating the positions of the 

 irregular transverse vessels. The stigmata are in some places arranged in complicated 

 spirals, while in others they form more or less regular transverse rows (PI. V. fig. 10). 



The dorsal tubercle (PL V. fig. 11) is much simpler than is usual in the genus. It is 

 not prominent, and the horns are not spirally coded, but merely turned posteriorly. The 

 peri tubercular area is large and irregularly triangular, the peripharyngeal bauds bounding 

 it laterally having an undulating course. 



The intestine (PI. V. fig. 9) is long and narrow, and the loop turns anteriorly towards 

 the branchial aperture, so as to partially enclose the left genital gland. 



One specimen was obtained at Port Jackson, Australia. Depth, 2 to 10 fathoms. 



Molgula pyriformis, Herdman (PL VI. figs. 1-3). 



Molguta pyriformis, Herdman, Preliminary Eeport, Proc. Boy. Soc. Edin., 1880-81, p. 236. 



E.iitTnid Appearance. — The body is pyriform or almost triangular, and is compressed 

 laterally; it is not attached. The anterior end is wide, straight, truncated, and has an 

 aperture at each extremity ; the posterior is narrow and pointed. The dorsal and ventral 

 edges are both convex. The widest point is at about one-third of the length from the 

 anterior end, and from this point the two edges taper rapidly to the narrow posterior end. 

 The apertures are at the extremities of the flat anterior end, they scarcely project, and 

 are inconspicuous. The branchial is rather the more anterior of the two, and the more 

 prominent, and is directed ventrally ; the atrial is quite sessile, and points anteriorly. 



The surface is entirely covered with a close coating of fine sand. 



The colour is dark brown (due to the sand). 



Length of the body, 2 cm. ; breadth of the body, I'.j cm. 



The Test is thin but stiff, and quite opaque. 



The Mantle is thin, with the musculature moderately developed. The strongest 

 bands are those that radiate from the bases of the branchial and atrial siphons. Over 

 the rest of the mantle the commonest form of muscle band is a short thick fusiform 

 clump of fibres. 



The Branchial Sac is delicate, with seven folds on the right side and six on the left. 

 These folds do not include the stigniatic part of the branchial sac, but are merely formed of 

 two or three additional internal longitudinal bars united by short transverse ducts, and 

 thus forming an open network. There are no transverse vessels distinct from the fine 

 intcrstigmatic tubes, but narrow horizontal membranes are present running transversely 

 from fold to fold across the intervening space. The fine interstigmatic vessels are 



