VAN NAME: SIMPLE ASCIDIANS. 523 
Branchial sac usually with six or more folds on each side. Stigmata 
straight, placed longitudinally, or in a few species transversely to the 
body axis. 
Intestine on left side forming a widely open loop. Stomach taper- 
ing gradually into the intestine. A liver generally present. 
Reproductive organs developed on both sides of body. 
Verrill (1879b) proposed the name Halocynthia as a substitute for 
the preoccupied but generally used name Cynthia. Both are, how- 
ever, long antedated by Pyura Molina, 1782, as shown by Michaelsen 
(1904). As above defined, this genus includes Boltenia Savigny, 1816, 
which has generally been kept distinct on account of its long stalk. 
Key to New England Species of Pyura. 
Body with a long slender stalk. Stigmata elongated transversely to the 
iMQl body axis ovifera. 
Body not stalked. 
Surface of the body with large branched processes. Stigmata elongated 
transversely to the body axis echinata. 
Surface of body evenly covered with very smaU tubercles, each bearing 
one or more minute points. Stigmata elongated in a direction parallel 
to the body axis aurantium. 
Pyura echinata (Linnaeus). 
PI. 54, fig. 61-65; PI. 70, figs. 143, 144; text-fig. 23. 
1767. Asddia echinata Linnaeus, Syst. Nat., ed. 12, vol. 1, pt. 2, p. 1087, 
% no. 6. 
1850. Ascidia hirsuta Agassiz, Proc. Amer. Assoc. Adv. Sci., vol. 2, p. 159. 
1854. Cynthia echinata Stimpson, Smithsonian Contr., vol. 6, p. 20. 
1867. Cynthia echinata Packard, Mem. Boston Soc. Nat. Hist., vol. 1, p. 277. 
1870. Cynthia echinata + C. hirsuta Binney, Gould's Invertebrata of Massa- 
chusetts, ed. 2, pp. 18, 20, pi. 23, fig. 326; pi. 24, fig. 336. 
1870. Cynthia (?) echinata + C. (?) hirsuta Dall, Proc. Boston Soc. Nat. Hist., 
vol. 13, p. 255. 
1871. Cynthia echinata Verrill, Amer. Journ. Sci., ser. 3, vol. 1, p. 96. 
1871. Cynthia hirsuta Verrill, Amer. Journ. Sci., ser. 3, vol. 2, p. 362. 
1872. Cynthia echinata Verrill, Bull. Essex Inst., vol. 3, p. 5. 
1872. Cynthia echinata Verrill, Amer. Journ. Sci., ser. 3, vol. 3, p. 213. 
1873. Cynthia echinata Verrill and Smith, Rept. on Invertebrate Animals of 
Vineyard Sound, pp. 495, 702. 
1874. Cynthia echinata Verrill, Proc. Amer. Assoc. Adv. Sci., vol. 22, pp. 
352, 363. 
1874. Cynthia echinata Veprill, Amer. Journ. Sci., ser. 3, vol. 7, pp. 43, 413. 
1879. Halocynthia echinata Verrill, Bull. U. S. Nat. Mus., no. 15, p. 148. 
