222 Southern Cross. 



(lisliuguisheil IVoiii other genera of its I'amily by the forwardly 

 directed head, the ch)se equality ia 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 referal)le to any described species, though, as will be 

 seen, it closely approaches one from Tierra del Fiiego. 



Family ENTOMOBRYIDAE. 



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 dentes, 2^ 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 Ije related to the common European and 

 American hotoma imlustris (Miiller) ; in that species, however, the 

 feelers are relatively longer and the mucro much shorter and thicker 

 than in this. 



No member ul' the yenus Isotoma was known outside tlie 

 Holarctic region until Lord Avebury in 1879 recorded an unde- 

 terminable species from Kerguelen.^ Kecently, however, several 

 species have been described by Schjiffer 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. Tiie feet of /. sikatica seem to agree almost exactly 

 with tliose of /. KJuvstadi. So do the antenna! segments in their 

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



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

 Trans., CLXVIII. (iST't), ]'. 21it. 



- CScbiiflcr, 'lIanibiir''t'iMa'4a]baen6ische Sammelreise: AiJterygoten,' Hamburg 

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



