Vou. 2] Ritter—The Pelagic Tunicata. 85 
Doliolum tritonis Herdman. 
Doliolum denticulatum Herdman, 1883, p. 101, Pls. 18, 19, and 20. 
Doliolum tritonis Herdman, 1888, p. 47, Pl. 3, fig. 3. 
Doliolum tritonis Traustedt, 1893, p. 4, Pl. I, fig. 10. 
Doliolum tritonis Borgert, 1894, p. 19, Pl. 5, figs. 17 and 18. 
Doliolum tritonis Borgert, 1901, p. III 3, fig. 3. 
Fig. 24.—Doliolum tritonis, gonozooid. 
(a) Gonozooid.—Fig. 24. Length, 15 mm., 12 mm., 12 mm., 
13 mm., 14 mm.; form very regular; test always very thin, and 
general consistency delicate. Lobes of branchial orifice prominent, 
rounded, somewhat broader than high, apparently always twelve; 
those of atrial orifice much less pronounced, usually two. Muscle 
bands eight, first and eighth considerably smaller, all excepting 
these two with a narrow line running lengthwise along the 
middle. Atrial orifice with ten very low, broad lobes, also 
rounded. Endostyle rather slender, extending from the middle 
of the second intermuscular space to a lttle beyond the middle 
of the fourth space; anterior end pinkish yellow in many speci- 
mens. Ganglion in the third intermuscular space, beyond the 
third muscle band about the width of the band. Hypophyseal 
duct long and slender, the mouth, which is rather small, situated 
a little in front of the middle of the second intermuscular space. 
Peripharyngeal band trending forward from the endostyle on 
each side in a broad curve which reaches in front of the second 
muscle band, then running backward again on the dorsal side 
of the right limb, passing into a broad open spiral behind the 
hypophyseal mouth. Dorsal limb of the branchial series begin- 
ning on a level with the ganglion a little behind the third muscle 
