67 



2. Summary and conclusions. 



The following section summarises, in a digestible form and for those who are not 

 specialists, the conclusions which may be drawn from the foregoing records; it deals only with 

 the species regarded in this Report as vahd. 



Since mere lists of positions, expressed as latitude and longitude, convey to most of 

 us little idea of the area thereby included, the records of the commoner species (excepting 

 bipundata) have been plotted as Charts I to VI ') and exhibit practically all the records, 

 whether definitive or not. They not only enable one to visualise the areas of horizontal distri- 

 bution, but bring out the amazing fact that between i6o°E. and 80° W. we have not a single 

 record of a Chaetognath, — at any rate so far as the present writer can find. 



Sagitta arctica Aurivillius. (Chart I). 



Localities"): 



Baffin's Bay and Davis' Strait; E. coast of Greenland to Spitzbergen, and to Faeroes Shetland 

 and Skagerak. 



Definitive o b s e r v a t i o n s ') : 



Neritic and occanic. 



N. limit: 8i°i4N., 22° 50' E. 



S. limit: 58° N., 11° E. (120 to 20 m.). 



Surface, bet ween 1° C. and 8° 5 C. 



Deepest haul : 500 to 200 m. 



Highest temperature: below 10° C. 



Lowest temperature: between 0° 3 and i°9 C. 



Whether the synonymy suggested above (p. 30 — 32) for this form be correct or not, 

 there can be little doubt but that it is a cold-water form. 



So far as its distribution goes, it is curiously like that of hamata : and the probability 

 is that it will be found, like hamata, to extend further South in the mesoplankton : this suggested 

 its possible identity with Zetesios. 



Sagitta Bedoti Bérancck. 



Localities: 



Malay (Siboga area) and Maldive Archipelagps; Japan. 



Definitive observati ons: 



Neritic ^]. 



Surface. 



Temperature: 28° to 29° C, and M.A. 21°. 



1) These have been picpared on, and leduced fiom, the Blank Charts puhlishcd by the Challenger Society for such purposes. 



2) These refer to mere geographical position, iirespective of depth. 



3) Undev this head are classed those few positive records which allow us to define the limit» of a species — in the present 

 state of our knowledge. For this purpose hauls with deep Vertical Nets are generally useless. 



4) It is perhaps not possible to describe the plankton of an Archipelago as either 'oceanic' or 'neritic". What are usually 

 supposcd to be truly oceanic conditions, depending on distance from land as well as on depth of water, can hardly apply to the case 



