Vou. 2] Ritter—The Pelagic Tunicata. 63 
with embryos on right side between fourth and fifth muscle 
bands. Testis, an elongated white mass in the intestinal ring 
closely applied to the intestine. Vas deferens given off from 
the middle of the testis, passing across the intestinal circle, and 
opening near the esophageal mouth. 
Down to the present time this has been one of the rarer of 
the early known species of salpa. It was described by Chamisso, 
by whom it was taken in the region of the Sandwich Islands. 
It did not occur in the Challenger collections, and has not until 
now been reported again from the Pacific, so far as I am aware. 
Meyer observed it, though not closely, nor in great abundance, 
about the Canary Islands, and we have several other ref- 
erences to its occurrence in the tropical and_ subtropical 
Atlantic. The Plankton Expedition took, according to Apstein, 
a total of nine specimens at two stations; one in the Gulf Stream, 
Lat. 41.6, the other in the Sargasso Sea, Lat. 31.5. Voigt, 1854, 
includes it in his list of species of the Mediterranean in the 
vicinity of Nice, but gives no further information about it. Its 
constant abundance on the southwestern coast of North America, 
in a plankton area at least adjacent to, if not in reality part of, 
that from which it was originally described, and its apparent 
rarity in other parts of the world, would seem to indicate that 
the headquarters of the species is here, though such a suggestion 
relative to the distribution of strictly pelagic organisms can 
have little value until supported by much more data than we 
yet possess. Despite the considerable differences between the 
Salpa here treated as C. affinis and any of the published descrip- 
tions and figures of the species, I am convinced of the correct- 
ness of the identification. All the discrepancies of any moment 
may be accounted for from the fact that the descriptions and 
figures hitherto published have probably all been made from 
museum specimens. For example, the straight long axis of the 
solitary generation as shown in the figures of Chamisso and 
Traustedt, give a wholly erroneous impression of the general 
form of the species, but the true shape as shown in lateral view, 
fig. 9, ean be fully appreciated only by examining the living 
swimming animal. Preserved specimens have more the form of 
the figures of the authors above mentioned. Again, the two 
