THE CH^TOGNATHA. 83 



the pages cited will give the necessary qualifications and the evidence. It is hardly 

 necessary to remark that all these statements refer exactly only to the area studied and 

 to the period of the cruise. They are not necessarily, many of them not even probably, 

 true for distant localities under different conditions. 



Sagitla serratodentata was epiplanktonic, extending from the surface to 100 fathoms, 

 with the highest number of average specimens at about 50 fathoms (p. 59). It showed 

 no indication of a nocturnal rise and diurnal fall (p. 60). On the contrary, although not 

 affected during the day by the actual light-intensity of the moment, still on the whole it 

 sought the surface by day and deserted it by night (p. 61). During or after rain it 

 abandoned the surface even in bright daylight, the largest number of specimens being 

 then found from 50 to 100 fathoms (p. 61). 



S. furcata was also epiplanktonic, with a maximum distribution between 50 and 

 100 fathoms (pp. 64, 81). Occasional specimens reached the surface and 25 fathoms, but 

 it was not taken below 200 fathoms (p. 64). 



S. macroaephala was purely mesoplanktonic, ranging from 400 (? 300) to 2000-1000 

 fathoms (pp. 65, 67). 



S. zetesios was also mesoplanktonic, ranging from 100 to 1000-750 fathoms (p. 68). 

 At less than 300 fathoms only small specimens were taken ; the large specimens were all 

 from, greater depths. 



S. bijnmctata, being apparently a neritic form, occurred very sparingly in the epi- 

 plankton (p. 70). 



^S*. decqyiens belonged to the upper mesoplankton ; it was taken with certainty only 

 between 100 and 200 fathoms (p. 70). 



Krohnia hamata was mesoplanktonic, never reaching as high as 25 fathoms, but 

 extending to the 2000-1500-fathom zone (p. 75). Above 500 fathoms only small 

 specimens of 5-17 mm. were found, extending into the lower epiplankton (p. 76) ; the 

 length of these smaller specimens on the whole increased with the depth, and 

 their maximum distribution was about 150-250 fathoms (pp. 76, 81). Only below 

 500 fathoms were large specimens to be found, mixed with a few small specimens, possibly 

 corpses. 



K. suhtUls occurred only in the upper mesoplankton and lower epiplankton, in too 

 small numbers for accurate deduction. 



Chajtognatha as a whole increased in numbers as one passed from the surface to 

 100 fathoms (p. 79), and diminished again in numbers between that level and 200 fathoms 

 (p. 80). At about 200 fathoms there was a sudden drop in the population, which then 

 remained fairly steady down to about 1000 fathoms (p. 80), with a possible indication of 

 a slight increase in the 750-500-fathom zone (p. 81). Below 1000 fathoms was a second 

 sudden drop (p. 80). Chaitognaths occur, however, in considerable numbers even at the 

 lowest zone studied, 2000-1500 fathoms (p. 80). 



In the following table the first three hauls refer to the mesoplankton trawl, the 

 remainder to tow-nets of " comparable " hauls. 



