PYCNOGONIDA 



By Isabella Gordon, D.Sc, Ph.D. 



British Museum (Natural History) 



(Text-figs. 1-75) 



INTRODUCTION 



THE Pycnogonida collected by the Royal Research Ships ' Discovery', ' Discovery II ' 

 and ' William Scoresby ' during the years 1925-31 far exceed in number and variety 

 those obtained by any previous Antarctic Expedition.^ Sixty-five species are represented, 

 all, with two exceptions, from the Western Antarctic and sub-Antarctic area. Of these, 

 fifteen species are described as new, a proportion of one in four approximately. One 

 genus is new and two {Pallene and Nymphopsis) are new to the area in question. Many 

 of the specimens of Decolopoda, Colossendeis and Ammothea are of unusually large size. 

 One feature of the collection is the abundance of minute forms, testifying to the 

 excellence of the method of using fine nets in conjunction with trawl or dredge. None 

 of the new species is of outstanding morphological or systematic interest, and the study 

 does not add much of phylogenetic importance. It may well be that, while future 

 expeditions will add to the number of species and to our knowledge of their geographical 

 distribution, the present conception of the Antarctic pycnogonidan fauna (from shallow 

 water) will not be materially altered. 



My best thanks are due to Prof. Ch. Gravier, of Paris, Dr A. Burr, of Strasbourg, 

 and Dr A. Panning, of Hamburg, who did all in their power to further my studies 

 during brief visits to the respective museums. A number of the commoner forms in 

 the earHer collection (1925-7) were identified by Dr W. T. Caiman, F.R.S., before 

 I began this study, but I am entirely responsible for the final determinations as well as 

 for all the conclusions arrived at in this report. I am under particular obligations to 

 Dr Caiman for his helpful criticism and encouragement. 



A number of the drawings were prepared by Miss Joyce Townend ; the others are 

 outline sketches drawn with the camera lucida. 



NOTES ON OCCURRENCE AND DISTRIBUTION 



A list of the Antarctic and sub-Antarctic species represented is given, together with 

 other data, in the following table (pp. 4, 5). 



As regards the numbers of individual specimens, out of a total exceeding 1800, at 

 least 1200 belong to the single genus Nymphon. Of these, three-fourths belong to the 

 two most common species A'^. aiistrale (500 +) and N. charcoti (300 +) ; two other forms 



1 See Caiman, 1915, p. i. 



