PYCNOGONIDA— CALMAN. 57 



" Terra Nova," all except three from a single station. The classification of these 

 presents difficulties that I have not been able to solve entirely to my own satisfaction. 

 The vast majority (after putting aside a few young specimens that I have not attempted 

 to refer to their species) can be grouped as shown in the following key, where the 

 groups are regarded as species related to A. communis (Bouvier). 



Ke2/ to the S'pecies of Achelia examined. 



a. Auxiliary claws less than half as long as principal claw. Ocular tubercle 



higher than wide, apex conical. 



a'. First three trunk-somites separated by articulation. Lateral processes 



sepai-ated. Chelophores extending to middle of proboscis . .A. spicata (Hodgson) 



b'. All trunk-somites coalesced. Lateral processes in contact. Chelo- 

 phores extending to one-third of length of proboscis . . .A. intermedia, sp. n. 



b. Auxiliary claws more than half as long as principal claw. Ocular tubercle 



not higher than wide, rounded, with an apical point. 



a'. Fii'st three trunk-somites separated by articulation. Chelophores 

 extending to middle of proboscis. Antero-lateral tubercles of 

 cephalon prominent ........ [A. communis (Bouvier)] 



U. All trunk-somites coalesced. Chelophores less than half as long as 



proboscis. Antero-lateral tubercles obscure or wanting . .A. brneei, sp. n. 



Unfortunately for the simplicity of this arrangement, however, there remain over 

 three specimens that, on account of differences in the segmentation of the body, are 

 excluded from all these categories, and there are a few others in which the agreement 

 with one or other of the species is not so obvious and complete as might be desired. 

 The number of these aberrant specimens is so small that it is perhaps justifiable to leave 

 them out of account as " abnormal," but, added to the variations that occur within the 

 groups here treated as specific, they tend to shake our confidence in the stability of 

 these groups. I am inclined to think that future work may result in ranking 

 A. intermedia as a form of A. spicata, and A. hrucei as a form of A. communis, if, indeed, 

 it be not found necessary to include all four under one specific name. 



Achelia spicata (Hodgson) (Text-figs. 13 and 14). 

 Austrotliea spicata, Hodgson, 1914-15, p. 147. 



Occurrence. — Station 220, off" Cape Adare, 45-50 fathoms; 23 $, 13 $. Station 

 355„McMurdo Sound, 300 fathoms ; 1 ?, 1 ^. 



Descripition. — Trunk hardly longer than its greatest width, across the second 

 lateral processes ; first two intersegmental articulations very distinct, third marked 

 only by a faint superficial groove. Lateral processes more or less well separated, the 

 last two pairs usually separated to the base ; a pair of dorsal tubercles, the posterior 

 the larger, on each of the first three lateral processes, and a small anterior tubercle 

 only on the last lateral process. Cephalon a little wider than long, without antero- 

 lateral tubercles. Ocular tubercle much higher than wide, inclined forwards, conieally 

 tapered above the eyes ; anterior pair of eyes not much larger than posterior. 



