44 
in which they have been captured is not clearly demonstrated by 
the present material. It is probable, however, that the fullgrown, 
mature specimens live and breed in very deep water; the eggs or 
the young individuals then rise. towards the upper strata, and 
when. maturity is approaching the animals seek towards the deep- 
sea again. 
Sagitta planktonis Steinhaus. 
Sagitta planctonis Steinhaus 1896, p. 39. 
— — Ritter-Zåhony 1911b, p. 29. 
—  planktonis Michael 1911, p. 44. 
—  planctonis Ritter-Zåhony 1914, p. 2. 
According to Ritter-Zåhony (1911b) this species is widely 
distributed in the mesoplankton of the oceans; young individuals 
may also be found in the lower epiplankton. As to the occurrence 
in the San Diego region Michael states (1911) that it is mainly 
found below 100 fms., but may be met with at the surface. The 
investigations of the "Ingolf", the "Thor", and the "Tjalfe" prove, 
that the distribution of the species in the northern Atlantic is sharply 
limited by the submarine ridges from Scotland over the Faeroes, 
Iceland, and Greenland, to Baffin Land. The northernmost locality, 
where the species has been found hitherto, is Lat. 65? 00' N, 
Long. 28” 10' W, just south of the Iceland —Greenland ridge (Rit- 
ter-Zåhony 1914). 
The "Tjalfe" expedition has brought home 20 specimens of 
this elegant species. One specimen, a young individual, was taken 
about 100 m below the surface at stat. 1 in the Atlantic between 
Scotland and Cape Farewell. The other specimens have been cap- 
tured in deep water off the west coast of Greenland. 
All specimens have been caught in the month of May. In the 
larger individuals the ovaries are very much prolonged, but ripe 
eg8gS are not present. The testes are mature at least in one, prob- 
ably in more specimens. 
The total length and the length of the ovaries in all specimens 
from the Davis Strait are given below (X means that the ovaries 
have not been measured): 
