400 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
languet may be present or wanting (wanting in the New England 
species). Atrial orifice often some distance posterior to the front end 
of the thorax. Stomach with longitudinal folds in the wall. Intestinal 
loop usually if not always twisted, bringing the stomach to the dorsal 
side, the rectvuii crossing the esophagus on the left side. 
ApHdium pallidum (Veriill). 
Text-fig. 22. 
1871. Amouroucium pallidum Verrill, Amer. Journ. Sci., ser. 3, vol. 1, p. 289. 
1871. Amouroucium pallidum Verrill, Amer. Journ. Sci., ser. 3, vol. 2, p. 362. 
1872. Amouroucium pallidum Verrill, Amer. Journ. Sci., ser. 3, vol. 3, p. 211. 
1873. Amaroecium pallidum Verrill and Smith, Report on Invertebrate 
Animals of Vineyard Sound, pp. 496, 705. 
1874. Amaroecium pallidum Verrill, Amer. Journ. Sci., ser. 3, vol. 7, pp. 40, 
43, 504. 
1874. Amaroecium pallidum Verrill, Proc. Amer. Assoc. Adv. Sci., vol. 22, 
pp. 357, 363. 
1879. Amaroecium pallidum Verrill, Preliminarj' Check-list of Marine Inverte- 
brates, p. 27. 
1886. ? Aplidium despectum Herdman, Report Voyage Challenger, Tunicata, 
pt. 2, p. 210, pi. 28, fig. 11-13. 
1891. Amaroucium pallidum + (probably) Aplidium despectum Herdman, 
Journ. Linn. Soc. London, Zool., vol. 23, pp. 628, 622. 
1901. Amaroucium pallidum Kingsley, Proc. Portland Soc. Nat. Hist., vol. 2, 
pt. 5, p. 183. 
1901. Amaroucium pallidum + (probably) Aplidium despectum, Whiteaves, 
Catalogue of Marine Invertebrata, p. 265. 
1909. Amaroucium pcdlidum -\- (probably) Aplidium despectum Hartmeyer, 
Bronn's Tier-reich, vol. 3, suppl., pp. 1469, 1477. 
As stated below, Aplidium lactcum Huitfeldt-Kaas, 1896, is very 
probably identical with this species. Its synonymy is as follows: 
1896. Apjlidium lacteum Huitfeldt-Kaas, Norske Nordhavs-Exp., Zool., 
vol. 23, no. 1, p. 15, pi. 2, fig. 14-16. 
1903. Aplidium lacteum Hartmeyer, in Romer and Schaudinn, Fauna Arc- 
tica, vol. 3, p. 3.38-340, text-figs. 46, 47, pi. 6, fig. 13; pi. 13, fig. 16. 
1907. Aplidium lacteum Redikorzew, Ann. Mus. Zool. Acad. Imp. Sci. St. 
Petersbourg, vol. 11, pp. 149, 153. 
1908. Aplidium lacteum Redikorzew, Trav. Soc. Nat. St. Petersbourg, vol. 
29, pp. 21, 34. 
1909. Aplidium lacteum Hartmeyer, Bronn's Tier-reich, vol. 3, suppl., p. 1469. 
"Masses sessile, hemispherical or subglobular, usually attached by 
