26 Canon A. M. Norman — Notes on the 



The antennae are furnished with three-jointed secondary 

 branches. 



Tlie second maxillipcds and otlier mouth-organs are some- 

 wliat similar to those of Thalestris frigidn. 



Tlie first pair of tlioracic feet are moderately short and 

 stout and the outer branches are distinctly shorter than the 

 inner ones (fig. 14) ; the spiniform seta on the outer distal 

 angle of the second basal joint is comparatively large, but the 

 spine on the inner distal angle is considerably smaller ; the 

 terminal claw of the inner branches is very long and slender 

 and the plumose seta which springs from near the middle of 

 the inner margin of the second joint is also elongated ; the 

 general structure and armature o£ both branches resemble 

 those of the first pair in ThaJestris rohusta, Claus, while the 

 second, third, and fouith pairs are somewhat similar to those 

 of Thohstris frigMa. 



The fifth pair (fig. 15) have also a general resemblance to 

 the fifth pair (f that species, but the basal joint is propor- 

 tionally rather broader at the base, and its armature is some- 

 what diflTerently arranged ; the arrangement of the armature 

 of the secondary joint is also somewhat different from that of 

 the secondary joints of the species referred to. 



The caudal furc£e are very short. 



(2) The male. — The male resembles the female, but is 

 rather smaller. The antennules have a modified structure to 

 fit tliem ibr grasping. The spine on the inner distal angle of 

 the second basal joints of the first pair of thoracic feet is 

 sliong and distinctly hooked at the end, as shown in PI. III. 

 fig. 14 a. 



The inner branches of the second pair of feet resemble 

 generally the same branches in the male of ThaJestris friyida^ 

 but they are distinctly broader in proportion to their length, 

 and there is a slight difference in their armature, as shown in 

 the drawing (fig. 16). 



The fifth pair also resemble somewhat those of the male of 

 the .species referred to, especially in their armature, but the 

 inner produced part of tiie basal joint is less prominent and 

 more broadly rounded and the secondary joint is rather 

 smaller (fig. 17). 



Hah. 13og Fiord ; not very common. 



This Thalcslris comes very near Th. fn'gida, and I was at 

 first inclined to regard it as belonging to tiiat species; but it 

 was Icund that the difference in the structure of the first pair 

 ot thoracic feet in both the male and female and of the inner 

 bjancl.esof the second ] air in the male was alone sufficient to 

 distinguish it from the species referred to. The structure of 



