222 Southern Cross. 



distinguished from other genera of its family by the forwardly 

 directed head, the close equality in length between the third and 

 fourth abdominal segments, and the entire absence of scales. 



As might have been expected, the Geikie Land Isotoma does not 

 seem to be referable to any described species, though, as will be 

 seen, it closely approaches one from Tierra del Fuego. 



Family ENTOMOBRYIDAJEI. 



Isotoma klovstadi. 



Plate XLVII., figs. 1-8. 



Antennae 1 • 6 times as long as the head, the second segment 

 slightly longer than the third, but markedly shorter than the fourth. 

 Eight ocelli on each side ; post-antennal organ elongate, about twice 

 as long as an ocellus. Feet without tenent hairs ; both upper and 

 lower claws without teeth ; third abdominal segment slightly longer 

 than the fourth. Spring (apparently borne on the fifth abdominal 

 segment) with very slender deutes, 2i times as long as the manu- 

 brium ; mucro narrow and elongate, with straight ventral edge, 

 prominent apical and sub-apical teeth, and two less prominent 

 dorsal teeth close together. 



Colour. — Dark blue-violet ; legs and spring yellowish-brown. 



Length. — 2 mm. 



This springtail seems to be related to the common European and 

 American Isotoma 2Mlnstris (Miiller) ; in that species, however, the 

 feelers are relatively longer and the mucro much shorter and thicker 

 than in this. 



No member of the genus Isotoma was known outside the 

 Holarctic region until Lord Avebury in 1879 recorded an unde- 

 terminable species from Kerguelen.^ liecently, however, several 

 species have been described by Schafter from the southern regions of 

 America, and it is one of his Fuegian Isotomae — /. silvatica"^ — that of 

 all hitherto known species seems the nearest to our insect from 

 Geikie Land. The feet of /. silvatica seem to agree almost exactly 

 with those of /. Klovstadi. So do the antennal segments in their 

 relative lengths. Only in the Antarctic insect the antennae as a 



^ Sir J. Lubbock, ' Collembola in "The Collections of Kerguelen Island,"' Phil. 

 Trans., CLXVIIl. (1879), p. 249. 



^ C. Schiiffer, ' Hamburger Magalhaensische Sammelreise: Apterygoten,' Hamburg 

 (1897), p. 18, figs. 34-7. 



