ON COLLEMBOLA FROM THE SOUTH ORKNEY ISLANDS. 55 



chitinised dorsal lobe or " galea " (fig. 4, ga.), terminating in three prominent teeth. 

 Ventral to this, and protruding beyond it, is a delicate falcate lamella (fig. 4, la.'), 

 fringed with long delicate hairs, while a smaller lamella, also fringed with fine hairs 

 (fig. 4, la."), lies internal to the galea. The palp (fig. 4, pa.) carries six prominent bristles, 

 the most distal being inserted on a long acuminate process. The stipes of the maxilla 

 (fig. 4, sti.) articulates with the cardo (fig. 4, car.), which is itself in connection, as 

 usual, with the supporting "foot" and ligament (fig. 4, pd. lig.) of the tongue 

 (fig. 4, lin.). 



Several at least of these characteristic features of the jaws in /. Brucei may also 

 be detected in its northern ally /. Beselsii. 



The form of the retinaculum in /. Brucei, as seen from the side, is shown under 

 high magnification in fig. 8. 



Isotoma octo-oculata, Willem, var. gracilis, nov. Plate, 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 specimen, 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 neigh- 

 bouring 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, 

 however (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 crassus, sp. nov. Plate, 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. 



* Recorded also by WAHLGKEN (1906) from South Shetland, Graham Land, and Panlet Island. 

 (ROY. soc. OP BDIN. PROC., VOL. xxvi., PP. 475-476.) 



