120 
PACIFIC SCIENCE, Vol. XIV, April I960 
Fig. 25. Variation in average number of specimens 
per haul of all species of tunicate for January, Febru- 
ary, and March, 1951. 
are lost, and curves have been continued to Sta- 
tion 84 (0400 hours), but are queried. High 
numbers were still present at 0400 and 0500 
hours, when sampling was discontinued. In- 
dividually, phorozooids, gonozooids, and old 
nurses show somewhat similar patterns to the 
average and to each other. More data are neces- 
sary to verify that the results illustrated are, in 
fact, the result of diurnal migration. Each of the 
peaks of numbers shows a degree of correlation 
with low tidal velocities which may not be coin- 
cidental, although reasons for this are not clear. 
TUNICATES AS INDICATOR SPECIES 
Results accruing from Lachlan samples on the 
use of salps as practical indicator species are 
meagre. Distinct preferences are apparent when 
occurrences are plotted against salinity and tem- 
perature (Figs. 21, 22) and some of these prob- 
ably would persist, even with more samples, 
e.g., as for Ihlea magaihanica and lasis zonaria. 
Most of the species of tunicates cannot be re- 
garded as practical indicators in that they occur 
so spasmodically. In conjunction with other 
'Indicator Species,’ as demonstrated in T-S-P 
diagrams, some of them provide useful addi- 
tional evidence of the presence of particular 
waters, e.g., Thalia democratica and Ihlea mag- 
aihanica. 
Distinctions between the faunas on either 
side of the subtropical convergence are not evi- 
dent from the distribution of the tunicates. 
On the other hand, distinct "coastal” and 
"oceanic” faunas appear to exist, the former 
consisting of Ihlea magaihanica and Oikopleura 
dioica , and the latter of most of the remaining 
species. How such relatively passive planktonts 
are able to maintain these distributional distinc- 
tions, especially in the strong tidal currents ex- 
isting about the southern coasts of New Zealand, 
is a problem. Boden ( 1952 ) , Hart ( 1953 ) , and 
Bary (1959#) suggest that differential circula- 
tion between near and offshore waters may exert 
considerable influences. 
SEASONAL DISTRIBUTION 
The very spasmodic appearance of the major- 
ity of species of tunicates makes It difficult to 
indicate the nature of their seasonal distribution 
for January, February, and March, 1951. Aver- 
age numbers taken per tow, of all species, do 
show a sharp increase to March (Fig. 25). This 
average condition, however, masks a number of 
species irregularities. For example, Pyrosoma 
atlanticum appeared late in January (one speci- 
men), and increased in numbers steadily to 
March; Salpa fusiformis f. asp era occurred in 
early January, again at the end of February, and 
again at the middle and end of March; Ihlea 
magaihanica occurred in January, and again in 
March, and so on. Some of the increases in the 
numbers of specimens are almost certainly sea- 
sonal, but irregularities such as result from the 
sampling of swarms tend to produce a mislead- 
ing picture for most species. To be reliable, data 
would need to be available from several seasons. 
Similar irregularities in catches, and their effects 
on curves of their distribution, are illustrated for 
several salps from the Barrier Reef by Russell 
and Colman ( 1935). 
SUMMARY 
Notes are given on the systematics of Oiko- 
pleura dioica and O. fusiformis , Doliolum ( Do - 
lioletta ) valdiviae, Pyrosoma atlanticum and 
P. spinosum , and of the salps lasis zonaria , 
Thalia democratica, Pegea confoederata , Salpa 
fusiformis f. aspera, and Ihlea magaihanica. The 
