VAN NAME: SIMPLE ASCIDIANS. 501 
ined. C. tenax has been collected near Bear Island and Hope Island, 
the Faroe Islands, and Greenland, in from 6 to 100 fathoms. It was 
not correctly reported from the West Indies, Herdman's statement 
to that effect being the result of a misunderstanding. 
Caesira arenata (Stimpson). 
PI. 50, fig. 39-42; Pi. 52, figs. 48, 49; PI. 71, fig. 150; text-fig. 15. 
1850. Ascidia psammophora Agassiz, Proc. Amer. Assoc. Adv. Sci., vol. 2, 
p. 159 (description insufficient). 
1852. Molgula arenata Stimpson, Proc. Boston Soc. Nat. Hist., vol. 4, p. 230. 
1860. Molgula arenata Stimpson, Smithsonian Check-list, p. 2. 
1869. Molgula arenata Perkins, Proc. Boston Soc. Nat. Hist., vol. 13, p. 160. 
1870. Molgula arenata + Ascidia psammophora Binney, Gould's Inverte- 
brata of Massachusetts, ed. 2, pp. 21, 24, pi. 24, figs. 330, 331. 
1870. Ascidia psammophora + Molgula arenata Dall, Proc. Boston Soc. Nat. 
Hist., vol. 13, p. 255. 
1870. Molgula arenata Verrill, Amer. Journ. Sci., ser. 2, vol. 49, p. 424. 
1871. Molgula arenata Verrill, Amer. Journ. Sci., ser. 3, vol. 2, p. 362. 
1872. Molgula psammophora Verrill, Amer. Journ. Sci., ser. 3, vol. 3, p. 213. 
1872. Molgula arenata Verrill, Amer. Journ. Sci., ser. 3, vol. 3, pi. 8, fig. 5. 
1873. Molgula arenata VerriU and Smith, Kept, on Invertebrate Animals 
of Vineyard Sound, pp. 699, 502. 
1889. Molgula arenata McDonald, Rept. U. S. Comm. Fish and Fisheries for 
1886, p. 858. 
1891. Eugyra arenata Herdman, Journ. Linn. Soc. London, Zool., vol. 23, 
p. 569. 
1909. Caesira arenata + C. psammophora Hartmeyer, Bronn's Tier-reich, 
vol. 3, suppl., p. 1324 (listed as uncertain species). 
1912. Caesira arenata Hartmeyer, Sitzungsb. Ges. naturforsch. Freunde, 
1912, no. 1, p. 15. 
1912. Caesira arenata Hartmeyer, Denkschr. K. Akad. Wiss. Wien, cl. 
math.-nat., vol. 88, p. 209. 
Agassiz (1850) in naming the species Ascidia psammophora gave no 
description sufficient to enable it to be recognized, saying" merely: 
"whose body is surrounded all over with fine sand. Found around 
Cape Cod" — a statement applicable to four or five different species. 
That he referred to the present one was not discoverable until Binney 
(1870) published two drawings of Agassiz's specimens made by Mr. 
Burkhardt, under Aga.ssiz's direction. Though these illustrations 
quite clearly represent this species, in the meantime Stimpson (1852) 
had published a brief but clear description of the species, enabling 
