600 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
1874. Ascidiopsis complanatus Verrill, Proc. Amer. Assoc. Adv. Sci., vol. 22, 
pp. 352, 355, 358, 363, 370. 
1874. Ascidiopsis complanatus Verrill, Amer. Journ. Sci., ser. 3, vol. 7, pp. 39, 
43, 413, 504. 
1874. Ascidiopsis complanatus Whiteaves, Amer. Journ. Sci., ser. 3, vol. 3, 
p. 5. 
1879. Ascidiopsis complanata Verrill and Rathbun, Proc. U. S. Nat. Mus., 
vol. 2, p. 231. 
1879. Ascidiopsis complanata Verrill, Bull. U. S. Nat. Mus., no. 15, p. 147. 
1882. Ascidiopsis complanatus Baird, Rept. U. S. Comm. Fish and Fisheries 
for 1879, p. 806. 
1885. Ascidiopsis complanata Verrill, Rept. U. S. Comm. Fish and Fisheries 
for 1883, p. 529. 
1889. Ascidiopsis complanata McDonald, Rept. U. S. Comm. Fish and 
Fisheries for 1886, p. 856. 
1891. Ascidia prunum + A. complanata Herdman, Journ. Linn. Soc. London, 
Zool., vol. 23, pp. 592, 594. 
1891. Ascidia callosa Packard, Labrador Coast, p. 396. 
1901. Ascidia (Ascidiopsis) complanata {A. callosa) Kingsley, Proc. Portland 
Soc. Nat. Hist., vol. 2, p. 183. 
1901. Ascidia complanata Whiteaves, Geol. Survey Canada, publ. no. 722, 
p. 266. 
1903. Ascidia prunum Hartmeyer, in Romer and Schaudinn, Fauna Arctica, 
vol. 3, p. 285, pi. 5, figs. 16, 17; pi. 13, fig. 1-5. 
1905. Ascidia prunum Bjerkan, Bergens Mus. Aarbog, 1905, no. 5, p. 15. 
1906. Ascidia prunum Redikorzew, Trav. Soc. Nat. St. Petersbourg, vol. 37, 
pp. 154, 310. 
1907- Ascidia prunum Redikorzew, Ann. Mus. Zool. Acad. St. Petersbourg, 
vol. 11, pp. 142, 151-153. 
1908. Ascidia prunum Bjerkan, Rep. Second Norwegian Arctic Exped., 
no. 14, p. 10. 
1908. Ascidia prunum Redikorzew, Trav. Soc. Nat. St. Petersbourg, vol. 39, 
pp. 20, 30. 
1908. Ascidia prunum Bjerkan, Tromsoe Mus. Aarshefter, no. 25, p. 83. 
1909. Phallusia prunum Hartmeyer, Bronn's Tier-reich, vol. 3, suppl., p. 1403. 
1910. Phallusia prunum Hartmeyer, Danmark-Expeditionen, vol. 5, p. 234. 
1912. Phallusia prunum Hartmeyer, Sitzungsb. Ges. Naturforsch. Freunde, 
1911, no. 10, pp. 439, 440. 
Not greatly different from the last described species (P. ohliqua) in 
external appearance though generally more regularly oval in outline, 
especially when young, and more flattened in a direction perpendicular 
to the surface of attachment, with the apertures less prominent and 
with a thicker, firmer, more cartilaginous test, which in young indi- 
viduals is very transparent, with a smooth surface, though in older 
specimens it becomes wrinkled, and often covered with hydroids, 
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