339 
Chaetognatha of the Monsoon Expedition — Alvarino 
12" E, from 2179 m depth). No typical Indian 
Ocean species was found. The sampling only 
covered the oceanic regions, and it is assumed 
that some neritic species of chaetognaths may 
be restricted to the Indian waters. 
Important previous works on the Chaetog- 
natha in the Indian Ocean and adjacent waters 
include: 
Number of valid 
Authority species observed 
Beraneck ( 1895), Bay of Amboine 5 
Burfield and Harvey (1926), Indian Ocean.... 15 
Doncaster ( 1903 ) , Maldive-Laccadive 
Archipelago 11 
Fowler ( 1906), Indian Ocean 18 
George (1952), Indian coastal waters 12 
Lele and Gae (1936), Bombay harbor... 3 
Oye ( 1918), Java Sea 12 
Rao (1958), Lawson’s Bay, Waltair, 
Bay of Bengal 13 
Rao and Ganapati (1958), off east coast 
of India and Ceylon 12 
Ritter-Zahony ( 1909), southern 
Indian Ocean 6 
(1910), southwest Australia 10 
(1911), Deutsche Siidpolar Expedition.... 17 
Schilp ( 1941 ), Indian Ocean 19 
Tokioka (1940), New South Wales 8 
( 1955 ) , NE Indian Ocean .... 13 
( 1956), Central Indian Ocean 13 
( 1956), Arafura Sea 9 
The chaetognaths observed in the Indian Ocean 
can be grouped as follows: 
a) Cosmopolitan (common to Atlantic, In- 
dian, and Pacific oceans ) : S. lyra, S. en- 
flata, S. hexaptera, S. minima, S. bipunc- 
tata, K. subtilis, K. pacifica, P. draco, S. 
gazellae, S. tasmanica. 
b) Cold-water representants : S. gazellae, S. 
tasmanica, E. hamata. 
c) Tropical-equatorial, and restricted to the 
Indo-Pacific waters: S. ferox, S. robusta, 
S. pacifica, S. pulchra, S. neglecta, S. bedoti, 
S. regularis . 
d) Mesoplanktonic: S. decipiens, S. planc- 
tonis, S. zetesios. 
e) Deep water: E. hamata (in low latitudes), 
E. fotvleri, E. bathypelagica. 
It is important to notice that Sagitta macro - 
cephala Fowler was not recorded here. The ab- 
sence of this species from the samples may be 
due to its scarcity and to the small number of 
deep samplings. It was previously recorded in 
the Indian Ocean by Fowler (1906), Burfield 
and Harvey (1926), and Schilp (1941). 
Sagitta gazellae, an oceanic species with a 
circumpolar distribution in the Antarctic and 
Subantarctic waters, enters the Atlantic, Indian, 
and Pacific oceans up to the Subtropical Con- 
vergence, often extending further north in deep 
levels in the Atlantic and Pacific (Alvarino, 
1964£) . In the Monsoon collections (Fig. 2), 
S. gazellae occurred as far north as 36° S — 98° 
E and 37° S — 71° E; whereas David (1958) 
reported it extending along the 90° E meridian 
from 63° S to approximately 41° 30' S ( Fig. 2 ) , 
and David ( 1959) from 66° 35' S to 42° 35' S 
(south of the Indian Ocean). The specimens of 
S. gazellae recorded in the Monsoon region 
might very well represent penetrations of the 
Subantarctic waters below the Subtropical. The 
penetration apparently does not extend farther 
north, because none were recorded at the mid- 
water trawl station 9 situated north of the sep- 
tentrional boundary of this species in the Indian 
Ocean, although the sampling went to 1878- 
2000 m deep. The northernmost records of S. 
gazellae in the Indian Ocean (David, 1955) 
were at 40° 30' S — 90° E, and in the Pacific at 
39° 20' S— 180° E and 38° 30' S— 126° W. 
At station 22 (37° 49.6' S— 85° 21.7' E) 
only young specimens 28-30 mm long at early 
maturity stage 1 were found; while at station 
25 (57° 43' S— 169° 12' E) some were 50-60 
mm long and still at maturity stage 1. In the 
Pacific, at station 29 (40° 37' S— 164° 08' W) 
the specimens were 20-30 mm in length, and 
at station 32 (28° 35.3' S— 158° 57.5' W) 
they were 20-30 mm long and at maturity 
stage 1. 
David ( 1955) points out that S. gazellae was 
occasionally taken north of the Subtropical Con- 
vergence at 41° 49.7' S — 18° 49.9' E, and that 
the hydrographical data showed a northward 
extension of the Subantarctic waters. The obser- 
vations in the Pacific (Alvarino, 1964£) showed 
the progression of the Subantarctic waters at 
deep levels far north of the Subtropical Con- 
