W. G. Von Xome — Bermuda Ascidians. 343 



length by l mm across, when somewhat contracted. Their tissues ai - e 

 yellow, the stomach orange, and in addition many of the cells in the 

 mantle contain brown pigment grains of irregular shape, especially 

 on the anterior part of the thorax. 



The musculature (not shown in fig. 16) is similar to that of I). 

 <■<' i >sulatiim though the longitudinal bands are rather more numer- 

 ous, and as in that species, it becomes very weak on the abdomen. 



The branchial sac has four rows of stigmata, the number in a row 

 exceeding 20 on each side. The tentacles are evidently arranged 

 much as in I), adriaticum (Von Drasche, 3). There is a circle of 

 eight large ones; a little further forward, and alternating with them, 

 eight smaller ones ; and still further forward one or more circles of 

 still smaller ones. 



The gland surrounding the intestine in this species differs from 

 that of D. capsulation. The tubules of which it consists run length- 

 wise of the intestine and lie parallel, to each other, surrounding the 

 intestine on all sides. As in the last mentioned species, they do not 

 branch. Anteriorly they are of small diameter but increase in size 

 as thev follow the intestine backward. After following it some dis- 

 tance they leave it and run toward the stomach. At a point near 

 the latter they converge and unite into the common duct. Along 

 the intestine they are thin-walled tubes composed of an epithelium 

 of flat hexagonal cells with nuclei which do not stain deeply. 

 After leaving the intestine they become suddenly smaller, with 

 thick walls and scarcely visible lumen, close to which the deeply 

 staining nuclei of the cells are placed, and they are provided with a 

 conspicuous basement membrane. 



Two colonies were collected in 1898 and several in 1001. The 

 exact localities were not recorded, but thev were no doubt taken at 

 points near the eastern end of the group of islands. One of the 

 colonies contained a few larva-. 



Distoma obscuratum, n. sp. 



Plate XLVIII. Figure 11. Plate LV1II. Figures 105 and 106. 



Two specimens of this species, which is nearly related to D. con- 

 vexum, but evidently quite distinct from it, were collected in May, 

 1901, growing on corals in rather shallow water in Castle Harbor. 

 They are of flattened form, measuring between 20 and 30 mm across, 

 and are 3 to 4 mm in thickness, with rounded ecl^es. Thev are of 

 a uniform greenish black color, entirely opaque, and of firm semi- 

 cartilaginous consistency. 



