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PACIFIC SCIENCE, Voi XVIII, January 1964 
S, bierii Alvarino 1961 
S. bipunctata Quoy and Gaimard 1827 
S. elegans Verrill 1873 
S. euneritica Alvarino 1961 
S. ferox Doncaster 1903 
S. gazellae Ritter-Zahony 1909 
S' hex apt era d'Orbigny 1834 
S' lyra Krohn 1853 
S. minima Grassi 1881 
S. pacifica Tokioka 1940 
S. pseudo serratodentata Tokioka 1939 
S. pule hr a Doncaster 1903 
S. regularis Aida 1897 
S. serippsae Alvarino 1962 
S' tasmanica Thomson 1947 
Mesoplanktonic: 
Sagitta decipiens Fowler 1905 
S' macro cephala Fowler 1905 
S' marri David 1956 
S. planctonis Steinhaus 1896 
S. zetesios Fowler 1905 
S' maxima (Conant) 1896 2 
Bathyplanktonic : 
Eukrohnia bathyantarctica David 1958 
E. bathypelagica Alvarino 1962 
E. fowleri Ritter-Zahony 1909 
E.hamata (Mobius) 1875 (in low 
latitudes ) 
2 It also appears often in the upper layers, due to 
phenomena to upwelling. 
Heterokrohnia mirabilis Ritter-Zahony 
1911 (recorded in the Pacific by Bieri, 
1959; Tchindonova, 1955) 
The species present below 200 m are cosmo- ■ 
politan in distribution ( inhabiting the Atlantic, 
Indian, and Pacific oceans), with the exception 
of E. bathyantarctica and S. marri , which were 
recorded circumpolarly in Antarctic waters; E. 
bathypelagica which appears to be restricted to 
the depths of the Pacific and Indian oceans, 
according to the present data (Alvarino, 1962, 
1 96-£), and Bathyspadella edentata, represented 
by one specimen from the Pacific (Tokioka, 
1939). 
Sagitta elegans and S. gazellae typify the 
arctic-subarctic and the antarctic-subantarctic 
waters respectively (Fig. 2). The arctic con- 
stitutes an ecological individuality because of 
its uniform conditions. S. elegans is the typical 
chaetognath of the upper 100-150 m of this 
region, extending into the northern part of both 
the Pacific and the Atlantic. The extension of 
the distribution of S. elegans appears to be con- 
trolled by the concentration of oxygen in the 
water. 5'. elegans extends in the Pacific to 38 °N. 
Here 297 plankton samples were studied from 
182 stations distributed along this northern Pa- 
cific region. S. elegans was found in only 128 
localities, and in each case it was concurrent 
Fig. 2. World distribution of S. elegans and S. gazellae. Location of the profiles that appear in this paper. 
