PYCNOGONIDA. (f t ipr 9 
By T. V. Hodgson, F.L.S. 
(10 Plates.) 
The collection of Pycnogonids brought from the Antarctic by the ‘ Discovery ’ is a 
large one, including as it does no less than twenty-eight species, three of which have 
been assigned to as many new genera. Only one species can be regarded as of morpho¬ 
logical importance, Pentanymphon antarcticum, which is now known to be abundant 
and to have a circumpolar distribution. It differs from the genus Nymphon only in 
the possession of an additional pair of legs. At first this was thought to be quite a 
novel feature in the morphology of the Pycnogonida, but the Scotch expedition brought 
another and much finer species from the South Orkneys. This proved to be identical 
with Decolopoda australis, described by Eights some seventy years ago, and taken at 
the South Shetlands. Eights’ work was lost for a long time, and though it has been 
noticed recently by modern zoologists, the reception afforded it was extremely curious, 
involving as it did the point-blank refusal to accept the possibility of the existence of 
a Pycnogonid with more than the orthodox four pairs of legs. Mr. L. J. Cole (7), who 
apparently looked with more sympathy on the work of a fellow-countryman, was the 
first to appreciate this discovery properly. The genus Leionymphon was defined by 
Professor Mobius for a large but immature specimen taken by the ‘Valdivia’ in the 
vicinity of Bouvet Island. It has been found necessary to re-cast this genus; as now 
defined it contains no less than eight species, including two which had been assigned 
to the genus Ammothea, and another which Professor Mobius thought should be placed 
in the genus Colossendeis. No less than five species were taken by the ‘ Discovery,’ 
and four of them are new. No true member of the genus Ammothea was seen, but two 
new species assigned to new genera, Austrodecus and Austroraptus, belong, as does the 
genus Leionymphon, to the family Ammotheidse as defined by Professor G. 0. Sars. 
Austrodecus is perhaps a close relation of Tanystylum, Miers, and is a curious little 
form with a slender and elongated proboscis, like the snout of a weevil beetle, no chelifori, 
six jointed palps, and small ovigers. Austroraptus is remarkable for its spurred body 
and the length of its lees. 
o o 
Rhynchothorax australis is another curious form; the only other species of the 
genus is found in the Mediterranean, but, notwithstanding certain differences, there 
does not seem to be any justification for giving the ‘ Discovery ’ species other than 
specific rank. 
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