68 SUMMARY OF CURRENT RESEARCHES RELATING TO 



minimum breadths were 4 • 7 mm. and 3 • 2 mm. respectively ; the mean 

 breadth to length ratio had risen to 0'87. As Aragao and Nuttall have 

 pointed out, the variability depends on the nutritive conditions. 



New Guinea Spiders.* — H. R. Hogg reports on a large collection 

 of spiders from Dutch Xew Guinea. There are twenty-seven genera 

 and forty-three species or sub-species. About eighteen appear to be 

 new. A new genus Exopalyates is established, intermediate between 

 the groups Delenete and Heteropodeaj, but near Falystes. As might 

 be expected from a district so well supplied with insect-life, the local 

 representatives of the various genera are particulaily powerful and well 

 developed, producing in closely allied species sucli differences as a 

 superabundance of maudil)ular teeth in groups like the Deleneae, where 

 the number has been generally considered a matter of more than specific 

 importance. 



Antarctic Pycnogonids.f — W. T. Caiman reports on the Pycno- 

 gonida collected by the British Antarctic ('Terra Nova') Expedition. 

 The collection far exceeds in extent that of any Antarctic Expedition 

 yet reported on. It comprises no fewer than forty-four species, all from 

 the Ross Sea area, with the exception of a specimen of Colossendeis 

 megaloni/x Hoek, dredged near the Falkland Islands. Eleven species 

 are described as new, while five others are identified with species only 

 very recently described in Hodgson's preliminary report on the Pycno- 

 gonids of the German South Polar Expedition. The Antarctic seas are 

 far richer in species of Pycnogonida than any similar area of the oceans. 

 As to numbers of individuals, it is noted that 200 specimens of Nymphon 

 austrah were obtained at a single station, and presumal)ly at a single 

 haul, but most of the species were obtained in very small numbers. 



Carpenter has expressed the view that Pycnogonida show great 

 plasticity, but Caiman doubts that they show more variation than many 

 groups of Crustaceans do. Doderleiu has attributed great importance,, 

 among the factors favouring the development of local races, varieties,. 

 and species in any group of animals, to the lack of "Yagilitat" or 

 power of wandering, and there are few groups of Arthropods that show 

 less of this power than the Pycnogonida. Although some species have 

 the power of swimming in the adult state, their efforts seem to be 

 awkward and inefficient, and none of the larvae are better adapted for 

 locomotion. Of all Pycnogonida hardly any can be less " vagile," as 

 adults or as larvae, than the species of Pycnogonuni ; yet not only 

 P. gaini, but also the common P. Uttorah, show that a species may 

 have a wide range and great constancy of specific characters. 



Caiman discusses the significance of decapodous Pycnogons which,, 

 with Carpenter, he holds to be a recent specialization, not a primitive 

 survival. Bouvier's criticism of this interpretation is considered, but 

 Caiman adheres to his position. Reference is made to an interesting 



* Trans. Zool. Soc. London, 1915, pp. 425-84 (18 figs.). 



t Brit. Antarctic (' Terra Nova ') Exped., 1910 (Zool.) iii. No. 1 (1915) pp. 1-74 

 22 figs.). 



