CHAETOGNATHA. 5 



Sagitta zetesios. 

 Saijitla zetesios, Fowler, Transactions of the Linnean Sociely, 2nd Series, Zoology, x. (1905), p. 67. 



To this species I refer, with very great hesitation, three specimens from tempera- 

 tures below zero (Centigrade). The numbers, the size, and the shape of the teeth and 

 jaws agreed fairly well with those of specimens already described, but the specimens 

 were in far too battered a condition for the determination to be reliable. 



Formulae : — 



Krohnia hamata, Moebius. 



These specimens were quite unmistakable. In some of the younger specimens 

 the older jaws showed the characteristic sagination figured by Strodtmann and 

 myself in northern specimens. 



Formulae, based on twenty specimens : — 



The actual observations are as follows. They have been arranged in order of 

 decreasing temperatures, which agrees, except for a single entry, with the order of 

 increasing latitude. 



