Vou. 2] Ritter.-—The Pelagic Tunicata. (5) 
(b) Aggregate (sexual) generation—Fig. 19. ‘Agreeing 
with solitary generation in general form, size, orifices, thickness 
and transparency of test, endostyle, gill, ganglon and hypo- 
physeal organ, and nucleus. The pair of long posterior pro- 
cesses constantly present in the asexual generation, not present 
here, but a few processes into which the mantel extends are found 
on various parts of the body, but wholly irregular as to location. 
Body muscles four, first three confluent dorsally, but each inter- 
rupted ventrally; the fourth bending abruptly forward on the 
ventral side. A band as broad as the body bands at the branchial 
orifice, situated some distance back from the orifice itself, and 
continuous around the animal except for an interruption on the 
ventral side. Laterally on each side a branch given off from this 
band extending postero-dorsad; also a delicate muscle on each 
side extending from the band toward and around the extreme 
of the orifice; a pair of delicate longitudinal muscles in dorsal 
lip. Posteriorly, a delicate muscle given off from the fourth 
body band on the dorsal side, and extending to a variable extent 
backward and downward in the region of the atrial siphon. A 
number of delicate muscles belonging to atrial orifice. Ovary 
situated on right side, midway between fourth muscle band and 
nucleus. 
In treating the muscles of this form I have followed the 
usual custom and enumerated four body muscles only. I strongly 
suspect, however, that in reality we have here six, as in the soli- 
tary form. On this view, the first muscle of the solitary form 
would be represented by the postero-lateral branches, fig. 19, 
of the sexual form; and the sixth of the solitary form would be 
represented by the delicate band given off from the fourth. 
The species is, next to fusiformis-runcinata, the most abun- 
dant in the area. It has been taken during every month in the 
year in which plankton collecting has been systematically done, 
and in all probability is always present. 
