_ 
in California’ and elsewhere have thus become numbered 
among the worst mammalian pests, inflicting enormous losses 
upon agriculture. These teeming Souslik populations have 
shown themselves to be liable to plague infection, and in this 
respect they constitute a very grave peril to the public health 
in many regions. 
Fossil remains of Cvztel/us were first discovered in the 
European Pleistocene by Kaup, who described (Oss. Foss. 1839, 
p. 112, Plate XXV., Figs. 3 and 4) a beautifully preserved 
skull, which was at first believed to have come from the 
Miocene Dinotherium Sand of Eppelsheim; this specimen 
formed the basis of Kaup’s Spermophilus superciliosus. In 
1842, Desnoyer and Prévost found abundant Souslik remains, 
which they referred to C. cztellus, in the Pleistocene bone- 
breccia of the caves and fissures of Montmorency. Dr Hugh 
Falconer in 1859 was the first to detect the genus among 
British fossils, and in his posthumous Padcontological Memoirs 
(vol. ii., p. 472, 1868) two lower jaws from the bone-caves 
of the Mendip Hills, and another from the brickearth at 
Fisherton near Salisbury, are described and figured. To the 
Mendip specimens Dr Falconer gave the name Spermophilus 
erythrogenoides, but recent study tends to show that this 
name must be treated as a synonym of superciliosus. Since 
these earliest discoveries, remains of Sousliks have been found 
in numerous British and Continental deposits of late 
Pleistocene age. Many specimens were obtained by Dr 
Blackmore from the Fisherton deposit, while other observers 
have found remains in the later deposits of the Middle Terrace 
of the Thames at Crayford and Erith, in the fissure deposits 
at Ightham, Kent, and in the Langwith Cave in Derbyshire 
(Cheadle, Proc. W. London Sct. Assoc., 1, p. 7, 1876; Newton, 
Quart. Journ. Geol. Soc., 50, 1894, pp. 94 and 55, and 1899, 
p- 422; Mullens, Derbyshire Arch@ol. Nat. Hist. Soc. Journ., 
1913, p. 15.) In 1882 Mr E. T. Newton described (Geol. Mag. 
[ii.] ix., p. 51) some fragmentary remains found by Mr Clement 
Reid in the ‘Arctic Freshwater Bed” at Mundesley, Norfolk, 
CITELLUS 723 
1 A most valuable account of the Ground Squirrels of California has been published 
recently by J. Grinnell and J. Dixon (Monthly Bulletin of the State Commission of 
Horticulture, Sacramento, vol. vii., pp. 597-708, 1919). 
