VAN NAME: SIMPLE ASCIDIANS. 
459 
The following form may be inseparable from this species or it may deserve 
recognition as a variety or subspecies. (See p. 464.) 
1870. Molgula producta Binney, Gould's Invertebrata of Massachusetts, ed. 
2, pi. 22, figs. 315, 316 (but not the description in text). 
1872. Molgula pellucida Verrill, Amer. Journ. Sci., ser. 3, vol. 3, pp. 211, 
289, pi. 8, fig. 2. 
1873. Molgula pellucida Verrill and Smith, Rept. on Invertebrate Animals 
of Vineyard Sound, pp. 699, 426, 429. 
1878. Molgula pellucida Coues and Yarrow, Proc. Acad. Nat. Sci., Phila- 
delphia, 1878, p. 303. 
1891. Molgula pellucida Herdman, Journ. Linn. Soc. London, Zool., vol. 23, 
p. 569 (listed as uncertain species). 
1909. Caesira pellucida Hartmeyer, Bronn's Tier-reich, vol. 3, suppl., p. 
1324 (li.sted as uncertain species). 
The writer cannot say whether or not the Molgula pellucida Verrill (?) of 
Metcalf (1900, p. 589) is this animal. 
Not Molgula pellucida Macdonald, 1859. 
Verrill (1871a, p. 58) and Verrill and Smith (1873, p. 700) give a 
detailed description of the external characters of the typical form of 
B. pilularis which is here quoted: 
" Body unattached, globular, covered with a thin layer of mud, and, 
when the tubes are retracted looking like a small soft ball of mud. 
Text-flg. 1. — Bostrichohranchus pilularis (Verrill). X 4. 
Integument of the body, when cleaned, very thin, soft, nearly trans- 
parent, thickly covered with minute granules, and minutely fibrous, 
usually concealed by the adhering particles of mud and fine sand, 
but this can be easily removed. The tubes are naked, nearly trans- 
parent, subconical, slender, as long as the diameter of the body, origi- 
nating close together and but slightly divergent, both of them nearly 
straight; they can be wholly retracted and their bases are surrounded 
and connected by a narrow, naked, oval, or oblong band, which is 
