36 K Canadian Arctic Expedition, 1918-18 



Anterior antennae 9-jointed, the 8th joint very small and a constant char- 

 ad eristic (Fig. 51). Mouth-parts normal; the first maxilliped is clawed like 

 ,the second, its claw being longer and more powerful than that of mp2; t he- 

 basal joint of mp 1 has three inner setigerous lobes of which the proximal wa> 

 observed with a single long thick soft seta, the other two having more than one 

 seta at their apices. 



Fig. 51. Dactylopusia signata. Anterior antenna. 



The first thoracic legs are like those of D. thisboides and D. neglecta; Hi 1 

 with a plumose si at the centre of the joint. The outer distal angles of Re 1 

 and 2 of the natatory legs are not conspicuously produced, as they are in D. 

 thisboides. Second legs with setae as in D. thisboides; the ectal spinules of He 

 are coarser than those of Ri; B2 with slender se and triangular acute ental 

 spur, a feature also found in D. thisboides; in p2 Ri 2 the slender proximal si 

 arises distad of the centre of the joint. Third legs: B2 with still slenderer >c 

 and very small ental spur. In the fourth legs the Ri 2 has only one si and this 

 appears to be distinctive. 



In the natatory legs p 2 to p 4 the terminal seta of the outer ramus is longer 

 than the entire ramus, in p 4 much longer. The se 3 has the same length as the 

 Re 3 in p 2 and p 4, a little shorter than the Re 3 in p 3. 



The fifth legs appear to differ from D. thisboides in the interrelative lengths 

 of the marginal spines, but the general correspondence is remarkably close 

 (Fig. 52). 



Fig. 52. Dactylopusia signata. Fifth leg. 



It might be supposed that this species may be a submature " instar " of 

 D. thisboides , but the structure of the first antennas is hard to reconcile with 

 such a supposition. A word must also be said about the character of the caudal 

 seta, which seems at the surface to offer an unequivocal distinction. On 

 consulting Claus's work on the free-living Copepods (Leipzig, 1863) at a distance 

 from my material, I found an exactly similar condition of the setae figured 

 for Thalestris forficula Glaus. This species is now placed by Sars in a new genus, 

 Microthalestris, and nothing is said about the " kolbig angeschwollen " bases of 



