HORN EXPEDITION—AVES. 
85 
their habits, and seem to be constantly on the move in quest of small insects which 
ferm their chief food. They are generally found either singly or in pairs.] 
No. 47. Calamanthus isabellinus, sub-sp. nov. Desert Lark. 
Pratincola canipestris, Gould, Proc. Zool. Soc. (1840), p. 171 (part.) 
Calamanthus campestris, Gould, Bds. Austr., fob, Vol. III., pi. 71 (1848) 
(part.) 
One adult male and female. Missionary Plain. Specimens from the hot plains 
of Central Australia are easily distinguished from examples obtained at Port 
Lincoln and the southern portions of the Australian continent by the uniform 
isabelline hue of their upper surface, and by their being but faintly and narrowly 
streaked above and below; the rufous colouring of the forehead too is much paler 
and extends on to the nape. I should have regarded the desert-inhabiting race as 
specifically distinct had I not examined a large series of specimens from different 
localities, and which exhibit a perfect gradation in colour and markings, from the 
dark and broadly-streaked form frecpienting marshy situations in the extreme 
southern portions of the continent, to the paler and far less conspicuously marked 
race found in Central Australia. I propose, however, to distinguish the latter 
form, in which the streaks on the upper surface are almost entirely lost, under the 
sub-specitic name of Calamanthus isabellinus. Total length 4‘5 inches, wing 2T5, 
tail 2, bill 0’5, tarsus 0‘9. 
The sexes are alike in plumage. 
Habitat. — Missionary Plain, Central Australia. 
Type. —In the Australian Museum, Sydney. 
Mr. Keartland’s note shows that the habits of the two races are entirely 
different from each other. 
[Far away from scrub or shelter of any kind two of these little birds were 
seen running over the stones or gibbers as actively and (quickly as Dottrel on the 
sea beach. How so small a bird, with its limited power of flight, manages to 
subsist on the scant supply of insects in such a place, and elude the vigilance of 
the numerous Hawks, is a mystery. Mr. Belt secured both birds, which proved to 
be male and female, between Adminga and Blood’s Creeks.] 
No. 48. Epiitiiianura aurifrons, Gould. Orange-fronted Ephthianura. 
Ephthianura aurifrons., Gould, Proc. Zool. Soc., 1837, p. 148; id., Bds. 
Austr., fob, Vol. III., pb 65 (1848); Sturt, Exped. Centr. Austr., Vol. II., 
