110 BULLETIN OF THE 



Very interesting is the Station 3414, J at 11.14 a. m., 350 miles S. E. of Aca- 

 pulco. Here were obtained in the open part of the Tanner net : — 



Number of 

 specimens. 



0-100 fathoms. Euphausia pellucida. 3 



0-200 fathoms. Thysanopoda agassizi. 1 



Euphausia mucronata. 2 



Euphausia pellucida. 32 



Nematoscelis microps. 1 



0-300 fathoms (nothing in Euphausia mucronata. 4 



the closed part of the Tanner Euphausia pellucida. 17 



net towed at that depth 15 Nematoscelis microps. 5 



minutes). Stylocheiron suhmi. 2 



Euphausia pellucida is the only species which comes in the daytime, 

 although in small numbers, near the surface of the sea, the other species swim- 

 ming at a greater depth. And, indeed, most of the E. pellucida are found by 

 day at a greater depth than 100 fathoms. On the other hand the catch from 

 to 300 fathoms contains no more specimens of this species than that from to 

 200 fathoms. It is therefore very probable that most specimens of E. 

 pellucida swim during the daytime in depths from 100 to 200 fathoms. It 

 seems that the species E. mucronata and Nematoscelis microps are under 

 analogous conditions ; they are wanting in the daytime in the zone of water 

 above 100 fathoms, but in the zone between 100 and 300 fathoms they are 

 present. 



Since other species are but rarely contained in the several catches, it is impos- 

 sible to get a good idea of their vertical distribution. But according to existing 

 data one may conclude that the most important and most abundant Schizopoda, 

 especially the species of the genus Euphausia, live in the daytime in a depth 

 from about 100 to 200 or 300 fathoms, and ascend at night to the surface. 2 



1 This locality, 350 miles from the nearest land, was the one selected for testing 

 the vertical distribution of the pelagic fauna by towing with the Tanner deep-sea 

 tow-net at depths of 100, 200, and 300 fathoms during the morning hours when the 

 surface species would naturally have sunk. See Bull. M. C. Z., Vol. XXIII. 

 No. 1, p. 52. — A. Agassiz. 



2 This agrees with the well known paucity of the surface fauna during the bright 

 hours of the day. Nearly all pelagic material is collected more abundantly at 

 night. — A. Agassiz. 



