HORN EXPEDITION—REPTILIA. 
113 
pores, in tlie relative dimensions of parts, and in the scaling. Full particulars are 
recorded in the account of each species. 
Adaptation to Environment .—This is most noticeable in the presumably 
protective colouration of the species of diurnal habits. Many of these exhibit a 
\'ery marked general rustiness, or even bright redness, in their general colouring, 
which is quite wanting in the forms met with in the south and east, and which 
agrees well with the colour of the red sands upon which they were captured. 
Definitions of Species .—It is the usual course of events for the species 
described from a new held to be apparently more sharply defined than are those 
from well-explored regions. When sufficient numbei’s of individuals have been 
examined with sufficient care, this sharpness disappears, and the definition of the 
species has almost always to be modified and extended, especially in the case of 
common or dominant forms. The result of fuller information and closer study is 
to cause the systematist to admit a considerable range of variation of characters 
into his definition of the species. Forms at first defined as distinct are found to 
be so linked together by intermediate forms that the true relationship between 
them is best expressed by combining them all under one specific designation, and 
distinguishing as named varieties or sub-species such groups as are of importance 
from their local occurrence, distinctness to the eye, or abundance. This process 
will no doubt take place largely in connection with our Australian lizards. Mr. 
Boulenger, in his admirable Catalogue, has set an example in this direction in the 
case of Delma fraseri, Lialis hurtonii, Ablephams l>outo?iii, and other wide-.spread 
species. In the present study we have had the wisdom of adopting this course 
borne in upon us in the case of sevei’al other lizards, especially of Egernia whitii 
and Hhiulia lesueurii. Thus we shall be prepared to include as varieties of the 
last-named H. spa/dingi, Macleay (= AT dorsalis, lllgr.), E[. lece, Blgr., AT stranchii, 
Blgr., H. inornafa, Gray, H. essingtonii, Gray, H. muelleri, Fischer, and H. 
tceniolata, White. There is the same kind of justification for this proposal as 
exists, e.g., for the union of the equally distinct forms Lacerta tiliguerta, L. lilfordii, 
L. oxycephala, &c., as varieties of Lacerta mnralis, which has been forced ujion 
European herpetologists. 
State of Preservation .—The large number of individuals collected during the 
Expedition were all in an excellent condition for examination. To have obtained, 
preserved, and conveyed under the exceptional circumstances so many specimens 
without damage speaks volumes for tlie skill and energy of Professor Spencer. 
We have to thank Professor Spencer for very kindly placing at our disposal 
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