138 
PACIFIC SCIENCE, Vol. XV, January 1961 
TABLE 1 
Collecting Station Data on Phleboranchiate Ascidians Examined 
Stations 20-61 were occupied by MacGinitie, stations B51-31 to B51-33 by Bohlke 
! 
SPECIMENS EXAMINED 
TYPE OF BOTTOM AND 
Chely- 
osoma 
Chely- 
STATION 
DEPTH 
REMARKS 
Ascidia 
macleay- 
osoma 
NUMBER 
DATE 
(ft.) 
(after MacGinitie, 1955) 
callosa 
anum 
iu ae quale 
20 
9 Sep 48 
125 
stones (sea urchins, Psolus, sea 
3 
anemones) 
23 
15 Sep 48 
130 
stones (sea anemones, Psolus, sea 
3 
urchins ) 
26 
9 Aug 49 
130 
stones, gravel 
1 
27 
9 Aug 49 
420 
stones, gravel 
1 
1 
32 
17 Aug 49 
741 
mud (worm tubes) 
1 
36 
6 Sep 49 
477 
few rocks (worm tubes) 
1 
37 
6 Sep 49 
227 
stones, large perforated rocks 
4 
42 
6 Oct 49 
216 
rocks, stones ( Psolus , sea urchins) 
2 
44 
1 1 Oct 49 
453 
rocks, stones, small amount of 
1 
2 
1 
gravel ( Psolus ) 
45 
1 1 Oct 49 
341 
stones, gravel, few rocks (sea 
urchins) 
1 
61 
5 Aug 50 
204 
mud, stones, gravel 
1 
B51-31 
29 Jul 51 ! 
151 
1 
B51-32 
29 Jul 51 
164 
2 
B51-33 
29 Jul 51 | 
144 
1 
(1943). Tunic highly variable with size, age, 
and environment; in smaller specimens less than 
1 mm. thick, membranous, colorless, trans- 
parent, smooth or slightly tuberculate, some- 
times papillate about the apertures; in larger 
individuals up to 9 mm. thick, gelatinous to 
cartilaginous, dirty tan to olive brown, often 
wrinkled and encrusted with debris. Siphons 
ranging from very short to nearly one-third of 
the total body length. Oral aperture with 6-8 
lobes, atrial with 6 lobes; some individuals 
with orange pigment spots between adjacent 
lobes on both siphons. Tentacles of 3 or 4 sizes, 
variable in number (Table 2), and regular to 
irregular in arrangement. Dorsal tubercle usu- 
ally with a U-shaped slit, the opening some- 
times canted toward the left; horns of the slit 
conspicuously outrolled in the largest specimen 
examined (sta. 44). Internal longitudinal ves- 
sels variable in number (Table 2), bearing 
both regular and intermediate papillae (the lat- 
ter often irregularly distributed). Transverse 
vessels of 5 orders present in larger specimen 
from sta. 42, the smallest order being parastig- 
matic, irregularly distributed, incompletely de- 
veloped, and corresponding in position to the 
intermediate papillae of the internal longitu- 
dinal vessels. Stigmata 2-20 per mesh. Renal 
vesicles forming a conspicuous layer of small 
bladders, particularly on the gut and adjacent 
mantle on the left side. Gonads well developed 
only in the 3 specimens from sta. 20 ( 1 speci- 
men, only 11 mm. long, bore a single row of 
large eggs in its oviduct), all of these with de- 
veloping larvae in the atrial chambers. 
DISCUSSION: This species has often been con- 
fused with Ascidia obliqua and A. prunum, 
which also occur in arctic waters. It differs from 
A. obliqua in bearing intermediate papillae on 
the internal longitudinal vessels and in its pos- 
session of abundant renal vesicles. It is dis- 
tinguished from A. prunum most conspicuously 
by its much smaller number of internal longitu- 
dinal vessels and by its habit of brooding 
