VoL. 2] Ritter —The Pelagic Tunicata. 101 
Turning to the ascidizooids, I have not had much better luck 
than with the colony as a whole. Thus the branchial siphons are 
said by Seeliger (‘‘Schlundrohr’’ of this writer) to reach a much 
ereater length in old zooids of giganteum than they ever do in 
atlanticum. In the same colony I find old zooids with long 
siphons, but others again, certainly equally old, as judged by 
position in the colony and development of the gonads, with the 
siphons decidedly short and wide. Of course it may not be Seeli- 
ger’s meaning that the siphon becomes elongate with age in all 
zooids. Indeed, this has been one of the considerations that has 
influenced my decision to call this gigantewm. The other point 
that has had weight with me concerns the arrangement of the 
zooids in the younger colonies. Seeliger states that in colonies 
of giganteum 8-9 mm. long three whorls of zooids, regularly 
placed above one another, are present; while in colonies of 
atlanticum of the same size the zooids are more numerous and 
smaller, and are not disposed with the same regularity. My 
youn colonies agree entirely with Seeliger’s account of the 
young giganteum. 
So far as concerns the branchial sac, the testes, and the mus- 
culature, upon which some reliance is placed by various writers 
for separating the two species, I am of the opinion that indi- 
vidual variation is so great here that the value of differences ean 
be determined only by extensive quantitative studies, careful 
regard being had to the age of the zooids. 
The color variation is also great, this ranging from deep pink 
to an entire absence of the color. No intimation of blue has 
been observed. On the whole, it seems that the older colonies 
are the more deeply colored. In fact, I have not seen any highly 
colored colonies less than 8 or 10 em. long. It is, however, true 
that one sees colonies of say 20 mm. length some of which are 
highly colored, while others of the same size are almost if not 
wholly without pigment. 
The species occurs in abundance throughout our area, at least 
from Mareh on through the summer and autumn months. 1! 
have records for December also, but a few only. It must be 
remembered, however, that we have thus far done but little 
winter collecting. 
