Pelagic Tunicata— Bary 
117 
specimens) and south (Lachlan specimens) may 
thus result from the different environmental 
conditions. 
The species made a sudden appearance, in 
large numbers, off Dunedin in early March (Fig. 
18*0 . Twelve days later several thousands of 
specimens were taken from near Cook Strait in 
waters of subtropical origin. There was a com- 
plete absence of specimens in either surface or 
oblique tows between the areas. Morphological 
distinctions of a consistent nature could not be 
shown between these groups. Nor was it pos- 
sible to demonstrate whether the concentrations 
were of similar origin. The plot of occurrences 
against salinities and temperatures (Fig. 21) in- 
dicates that the species was collected from a 
narrow range of salinity and from the warmest 
water. Indications are that the species is a warm- 
water one, which would be in accord with pre- 
viously known facts of its distribution. For ex- 
ample, Thompson (1942, 1948) states that 
T. democratica occurred between temperatures 
of 11.0° and 25.6° C, but in very much smaller 
numbers in the cooler Tasmanian waters ( limit, 
44° S.) than in waters further north. Although 
New Zealand collections were from further 
south than those in Australia the lowest tem- 
perature was about 12.75° C. which is above the 
lower limit given by Thompson. 
Salpa fusiformis f. asp era 
Metcalf (1918) records S. fusiformis f. aspera 
as widespread in Atlantic, Pacific, and Indian 
oceans, from equatorial waters to those of high 
latitudes. Thompson (1948) records four speci- 
mens of f. aspera, but very large numbers of 
S. fusiformis from southeast Australia (he also 
took S. fusiformis from stomachs of "blue cod” 
( Parapercis colias) caught in western Cook 
Strait, New Zealand, in 1940). Lachlan speci- 
mens were entirely f. aspera, which reverses the 
order of catch recorded by Thompson, and is in 
line with Metcalf’s statement that aspera was 
more abundant than the smooth form in his 
catches. 
Specimens were collected from Cook Strait 
(in January) to the subantarctic (Station 826) 
where a considerable catch was made (Figs. 
18c; 19c, d) . The occurrences, plotted against 
salinity and temperature (Fig. 21), show that 
specimens were captured from salinities com- 
mensurate with those of water of subantarctic 
origin. They occurred over a wide range of tem- 
perature, but even so, the T-S-P diagram strongly 
suggests a subantarctic origin. Both tempera- 
ture and salinity ranges include Stations 322 
and 326. Specimens at these stations, which are 
north of the subtropical convergence, may have 
reached the surface from water of subantarc- 
tic origin lying below the surface subtropical 
water (Bary, 1959#). 
Ihlea magalhanica 
This species was present in very large num- 
bers off southeast Australia, with highest concen- 
tration off eastern Tasmania where it replaced 
Th. democratica (Thompson, 1948). Thompson 
also recorded it as the only salp from a collection 
made in 1942 from northern South Island, New 
Zealand. Previous to these records, it was re- 
garded as rare, being known only from the Cape 
of Good Hope and Strait of Magellan, from 
near Kaiser Wilhelm Land and from off the 
south of South America (Metcalf, 1918; Thomp- 
son, 1948). Sewell (1926) is quoted by Thomp- 
son as saying the genus Ihlea has probably 
adopted a cold-water habitat and that its surface 
distribution is limited, at any rate largely, to 
circumpolar regions. 
Thompson (1948) in discussing the Aus- 
tralian records of Ihlea magalhanica concludes 
that "it is one of the salp species which has a 
low tolerance of warm-water conditions” and, 
"this species will therefore probably be useful 
as an indicator of any northern extension of the 
colder type of water conditions which may from 
time to time occur.” The temperatures in the 
region of its occurrences ranged between 11.6° 
and 22.25° C, the lower limit being relatively 
cool, for Australian conditions. He regards it as 
limited almost entirely to the upper 50 m. of 
water and states that maximum numbers oc- 
curred between October and February. 
Twenty-five Lachlan samples yielded 1,192 
specimens. Their distribution shows fairly con- 
clusively that I. magalhanica is a warm-water 
rather than a cold-water species, at least about 
New Zealand. Its occurrences were in the warm- 
est water (Figs. 18^, h; 19 d)\ these included 
Station 326 outside of the immediate vicinity of 
