ON COLLEMBOLA FROM THE SOUTH ORKNEY ISLANDS. 59 



it is another mark of high antiquity. It seems probable, therefore, that /. Brucei is 

 older than the typically Antarctic species ; and that, for the land-connections over which 

 its ancestors travelled, we must go back to early Secondary times. 



It is startling to conclude that these frail insects of the far north and the remote 

 south, now separated by thousands of miles of land and sea and ice, have passed through 

 so great a length of geological time with such slight structural deviation from their 

 common progenitors. 



REFERENCES. 



1905. W. S. BRUCB, " Bathymetrical Survey of the South Atlantic Ocean and Weddell Sea," Scot. Qeog. 



Mag., August 1905. 

 1899. G. H. CARPENTER and W. EVANS, "The Collembola and Thysanura of the Edinburgh District," 



Proc. R. Phys. Soc. Edin., vol. xiv., 1899, pp. 221-266, pis. v.-viii. 



1902. G. H. CARPENTER, " Inserta Aptera," in Report on the Collections of Natural History made in the 



Antarctic Regions during the Voyage of the "Southern Cross," pp. 221-3, pi. xlvii., London 

 (British Museum), 1902. 



1903. G. ENDERLEIN, "Die Insekten und Arachnoideen der Kerguelen," in Wissenschaftliche Ergebnisse 



der deutsclien tie/see Expedition auf dem Dampfer " Valdima," 1898-9, vol. iii. pp. 199-248, 

 taf. xxi.-xxxvii., Jena, 1903. 



1899. J. W. FOLSOM, "The Anatomy and Physiology of the Mouth-parts of the Collembolan, Orchesella 



cincta, Linn.," Bull. Mus. Comp. Zool. Harvard, vol. xxxv., 1899, No. 2. 



1905. F. W. HUTTOV, "Ancient Antarctica," Nature, vol. Ixxii., 1905, pp. 244-5. 



1891. H. VON JEERING, "On the Ancient Relations between New Zealand and South America," Trans. 

 Proc. N. Zeal. Imt., vol. xxiv., 1891, pp. 431-445. 



1904. A. ORTMANN, Reports on the Princeton University Expeditions to Patagonia, 1896-1899, vol. iv., 



"Palaeontology," Part 2, "Tertiary Invertebrates," pp. 45-332, pis. xi.-xxxix., Princeton, 

 1904. 

 1897. C. SCHAFFER, " Apterygoten," Hamburger magalhaensische Sammelreise, Hamburg, 1897. 



1900. C. SCHAFFER, "Die arktischen und subarktischen Collembola," Romer and Schaudinn's Fauna 



Arctica, pp. 237-258, Jena, 1900. 



1902. G. SCHOTT, " Oceanographie und maritime Meteorologie," in Wiss. Ergeb. Exped. " Valdima," 

 Jena, 1902, 



1906. E. WAHLGREN, " Antarktische und subantarktische Collembolen gesammelt von der schwedischen 



Siidpolarexpedition," Wissens. Krgtbn. der schioed. Sudpolarexpedition, 1901-3, vol. v., 1906. 

 1900. V. WILLEM, "Recherches sur les Collemboles et les Thysanoures," Mem. Com. Acad. Roy. Sci. 



Belg., vol. Iviii., 1900. 

 1902. V. WILLEM, "Collemboles: Resultats du voyage de S.Y. Belgica en 1897, 1898, 1899, sous le 



commandement de A. de Gerlache de Gomery," Rapports scientifiques, Anvers, 1902. 



DESCRIPTION OF PLATE. 



Fig. 1. Isotoma Brucei, side view, x 40. 



Fig. 2. Do. left side of head, dorsal view, showing ocelli, feeler, antennal organ (a. o.), and post- 

 antennal organ (p. a. o.), x 100. 



Fig. 3. Do. right mandible, ventral view, x 200 ; ap., apical teeth ; mo., grinding surface. 

 (ROY. soc. OP EDIN. PROC., VOL. xxvi., PP. 481-482.) 



