47 6 Proceedings of Iioyal Society of Edinburgh. [sess. 
Isotoma octo-oculata, Willem, var. gracilis, nov. PL II. figs 9-12. 
Length 1 *5 mm. Differs from the type by the short sub-crescentic 
ridge surrounding the post-antennal organ (fig. 10, p. a. o .) and the 
slender mucro of the spring, with its anterior dorsal tooth pointed 
and prominent (fig. 12). In this latter character the present 
variety agrees with that described from Kerguelen by Enderlein 
(1903). 
Localities. — Laurie Island, on cliff and moss 200 feet, one speci- 
men, 18th December 1903 ; Saddle Island, one young specimen, 
4th February 1903. 
As only two specimens can be detected in the collection, this 
is presumably a scarce species in the South Orkneys. The type-form 
was described by Willem (1902) from insects collected on the 
shores of Gerlache Strait, between Danco Land and neighbouring 
islands,* and a sub-species, Kerguelensis , has since been described, 
as mentioned above, by Enderlein. In the form of its mucro our 
insect agrees with the latter, from which, as well as from the 
type-form, it may be readily distinguished by the short and relatively 
broad post-antennal organ. According to Enderlein’s figure, how- 
ever (1903, taf. xxxvi. fig. 66), the organ is broader and shorter in 
the var. Kerguelensis than in the type (Willem, 1902, pi. iv. fig. 11). 
Cryptopygus crcissus, sp. nov. PL II. figs. 13-23. 
Length 2 mm. Post-antennal organ elongate, crescentic. Six 
ocelli on each side of head (fig. 16). Feet with two tenent hairs, 
not clubbed at the tip, and with untoothed claws (fig. 17). Spring 
with mucro one- third length of dens, bearing two slight teeth, 
a terminal and a dorsal (fig. 21). Colour very deep blue-violet, 
almost black in adult specimens. 
Localities. — Saddle Island, innumerable specimens, 4th February 
1903; Laurie Island, two specimens in moss on cliff 200 feet, 
18th December 1903. 
The remarkable genus Cryptopygus, showing affinities to Anuro- 
phorus and to Isotoma, was erected by Willem (1902) for a new 
species of springtail ( C . antarcticus ) found in numbers on the shores 
* Recorded also by Wahlgren (1906) from South Shetland, Graham Land 
and Paulet Island. 
