VAN NAME: SIMPLE ASCIDIANS. 509 
axial part of each gonad consists of an elongated flask-shaped, slightly 
curved ovary, whose walls are more or less evidently thrown into 
transverse plications. The opening for the discharge of the eggs is 
at the smaller and more dorsally situated end and is not at all pro- 
duced into an oviduct. The axis of the ovary of the left side is 
nearly dorso-ventral in direction, that of the right much less inclined 
to the horizontal. The blind end of the right gonad is not bent down 
around the end of the kidney as in C arenata (Stimpson). The 
numerous lobate testes surround almost the entire border of the 
ovaries. 
The only two good specimens of this animal in the collections came, 
if correctly labeled, from the channel at Wood's Hole, Massachusetts, 
and hence from water of very moderate depth, disturbed by strong 
tidal currents. They were collected by the U. S. Fish Commission 
in 1875. Two other specimens, about the size of the smaller of the 
two just described, labeled Martha's Vineyard, 1871, and Vineyard 
Sound, respectively, are also apparently of the same species, but the 
internal organs are in a very poor state of preservation, and the bran- 
chial sac and gonads not in a condition to show anything of their 
structure. The species is evidently very closely allied to C. arenata 
(Stimpson), described on page 501 yet with the material at hand, it 
does not seem justifiable to consider the two identical. 
Caesira retortiformis (VerriU). 
PI. 52, fig. 50-52; PL 69, figs. 139, 140; text-figs. 18, 19. 
1871. Molgula retortiformis VerriU, Amer. Journ. Sci., ser. 3, vol. 1, p. 56, 
fig. 3. 
1872. Molgula retortiformis VerriU, Bull. Essex Inst., vol. 3, p. 5 (no descrip- 
tion). 
1872. Molgula retortiformis Verrill, Amer. Journ. Sci., ser. 3, vol. 3, p. 211. 
1873. Molgula retortiformis Verrill, Amer. Journ. Sci., ser. 3, vol. 6, pp. 435, 
440. 
1874. Molgula retortiformis Verrill, Proc. Amer. Assoc. Adv. Sci., vol. 22, 
pp. 352, 363. 
1874. Molgula retortiformis Verrill, Amer. Journ. Sci., ser. 3, vol. 7, pp. 43, 
413, 504. 
1879. Molgula retortiformis Verrill, Preliminary Check-list of Marine Inverte- 
brates, p. 27. 
1879. Molgula retortiformis Verrill and Rathbun, Proc. U. S. Nat. Mus., 
vol. 2, p. 231. 
