The Pelagic Tunicata of the Gulf Stream. 77 
The following characteristics in respect to the muscles are distinctive 
of S. floridana: Muscles 4, 5, and 7 meet near the middle line of the dorsal 
surface to form a common trunk, which does not cross the middle line nor 
meet its fellow of the opposite side. Muscles 6, 7, 8, 9, and 10 meet on the 
middle line of the ventral surface to form a common trunk which crosses 
the middle line and unites with its fellow of the opposite side. Muscle 11 
is independent of other muscles, and its halves are separated from each other, 
both dorsally and ventrally. Muscle 12 crosses the middle line of the ventral 
surface, but its ends are independent near the middle line of the dorsal sur- 
face. Muscle 13 is complete both dorsally and ventrally and free from 
union with other muscles. It crosses, but does not unite with, muscle 14. 
Muscle 14 arises on the middle line of the ventral surface, from the middle 
of muscle 12, in a short longitudinal stem, which quickly divides into a 
pair of slender muscles, which, running outwards and backwards, bend 
around on to the dorsal surface and unite with muscle 15. Muscle 15 is 
a slender muscle which crosses the middle line of the ventral surface and 
unites, on the dorsal surface, with muscle 14 to form a single dorsal muscle. 
The method of muscle-enumeration that I have employed is the one 
that is best suited for discussing the homologies of the muscles in different 
species, and I give a table to show the difference between Apstein’s enumera- 
tion and my own. 
Table to contrast Apstein’s enumeration of the muscles of the solitary Salpa floridana 
with author’s enumeration. 
BROOKS. APSTEIN. 
WitISClEWe tin. cy.7a oatetesctteieret 1 on dorsal surface of figures 3 and 4; part of 2-3 on ventral 
surface of figure 3. 
WhtiSeles 2's .c-arstevaveetelemrti ee Part of 2 on dorsal surface of figure 4; part of 2-4 on dorsal 
surface of figure 3. 
MimtSC1e%.3 aisha Actas) heeits sles 2 on dorsal surface of figure 4; I on ventral surface of fig- 
ure 3. 
INIISCIGRAl errs icrecierssrcriers Part of 2 in figure 4; part of 2-3 in figure 3. 
MiitSClegiS 55. aicte's ache aetet 3 in figure 4; part of 2-4 on dorsal surface of figure 3; part 
of 2-3 on ventral surface of figure 3. 
Minsele i622 28). cacleniee st Part of 2-3 on ventral surface of figure 3. 
Muscles 72 sreiaoleetecus Sal 4 in figure 4; 2-4 on dorsal surface of figure 3; 4-5 on ventral 
surface of figure 3. 
MiusclenS3 5, smeclecitess. 5 in figure 4; 5 on dorsal surface of figure 3; 4-5 on ventral 
surface of figure 3. 
WSC LES Ole erc cst oretasicionvere Muscle 6 in all figures. 
INETISCI EMO gets osias eine Muscle 7 in all figures. 
Miasclegtisy. o5 2 tiecet es Muscle 8 in all figures. 
INMiSClen 12 terscirc Sew cate Muscle 9g in all figures. 
Mirscle= 13585 ols oe omer © Muscle 10 on dorsal surface in figures 3 and 4. 
WEUSCLE IT Alar: felexcts,<sistere's « Muscle 10 on ventral surface of figure 3. 
MiGSCIEv TE a. csterectcrercs ina Not designated nor represented correctly. 
MSC less Ormntat vod ec heae Not figured nor noted. 
In plate 1, figure 4, I give a ventral view of an old embryo 4.5 mm. long, 
magnified 30 diameters. It is in the same stage of development as the one 
on which Apstein bases his account of the species. The muscles are es- 
sentially like those of the adult, except that muscles 12, 13 and 14, are rela- 
