STUDY OF LIZARDS 



Identification. 



The illustration showing the arrangement and names of the scales, es' 

 pecially those on the head, should be studied carefully. Since the names and 

 positions of several of the head scales are the same as those of the snakes and 

 correspond to the bones of the mammal skull, this is not a very difficult task. 

 Some li2;ards have bead'like scales on the body, others have smooth but polished 

 ones, and others have rough scales with projecting rear edges. Some forms 

 have large scales above and small ones on the belly, while others reverse the 

 arrangement. 



Pattern is somewhat variable and depends partly upon age. Colors also 

 vary, frequently with the emotional condition of the animal, and usually fade 

 very badly in preserved specimens, which are commonly as disappointing as 

 a collection of preserved fish. Many museums find colored casts much more 

 useful for educational purposes than the best preserved or mounted originals. 



Measurement of total length needs no explanation. However, the loss 

 of part of the tail frequently detracts from the usefulness of this character. 

 The length of the head is the straight distance from the tip of the snout to 

 the rear of the ear opening or of the tympanum, that of the tail from anus 

 to tip. 



General habits. 



The studies now in progress on optimum and maximum temperatures for 

 difi"erent reptiles are yielding rather surprising results, and should be checked 

 in various localities. Food preferences also need study. Some lizards are rc' 

 corded as insectivorous, some as carnivorous, and some as herbivorous. These 

 records may be correct, but observations on free animals and those on caged 

 animals often show great differences. A captive animal may have little choice 

 except to eat the food offered it or to starve. Since birds have enjoyed legal 

 protection, we have developed more humane methods of bird study, and it 

 is well to remember that field glasses and Indian-type stalking may be used 

 on other animals besides birds. Banding could doubtless be adapted to lizards, 

 to learn their individual ranges and life spans. Other problems will soon 

 suggest themselves. For example, one might check the often repeated state- 

 ment that scalation on a regenerating tail, if different from the original pat- 

 tern, resembles that of a more primitive group of lizards. Voice is also of 

 interest. Some writers state that the geckos are the only lizards with any 

 vocal powers beyond a hiss or grunt. Barking lizards are mentioned in travelers' 

 stories. Do other lizards '"hark"", or are the voices those of small rodents which 

 may share the burrow or retreat? 



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