644 REPTILES AND AMPHIBIANS. 
Valley, as first pointed out by Agassiz for Turtles, and afterwards di- 
vided by Cope, into an Eastern, Southern, and Western fauna. 
Finally, in regard to classification, the study of these animals has been 
rendered needlessly complicated. Naturalists have seemed so eager to 
append their names to a new species that, instead of examining to see 
what others had done before them, they affixed a new name to a large 
per cent , at least, of the animals met. The truth of this statement is 
evident fromthe abundant synonyms by which nearly all these animals 
are known. In some casesagain,the most careful and conscientious observ- 
ers have been misled, and considered varietal differences specific charac- 
istics. Such a principle followed out in regard to the human race would 
give us numerous species of men founded on as valid grounds as have 
been many of the species of animals. Moreover, in regard to the separa- 
tion of these animals into genera, families, sub-orders, etc., naturalists 
have changed each others names and arrangement, often for better, but 
too many times apparently for the sake simply of a change, and to the 
disadvantage of science. 
In selecting marks of species, families, and orders, much difficulty must 
be experienced. To any one who has made a careful and thoughtful 
study of osteological characters, these, though among the best, are insuf- 
ficient. Thus the bones of the same animal vary, not only in the extent 
of ossification, but in number withage. Nor arethe anatomical relations 
of the soft parts any more valid. Let a person examine the structure of. 
a frog and tadpole, and he would unquestionably pronounce them to be 
distinct species. On the other hand the teeth, their shape, presence or 
absence, the matter of having a grooved or hollow poison iang, indicate a 
habit of the animal, and are, to a certain extent at least, valuable grounds 
of classification. The same remark will apply to the presence or absence 
of a tongue in the Amphibians, its shape and attachments, and whether 
protrusible or not, so asto become an instrument of prehension. Ina 
similar manner the palmation of the toes indicating an aquatic ani- 
mal, and the dilatation of the tips showing an arboreal habit, the pro- 
jecting rostral in Heterodon, the soft shell and prolonged nostrils in the 
Trionychidx, the presence of parotoids, the granulation of the abdomen, ~ 
the covering of the head, the scales whether carinate or not, the presence 
of spines or thorns, and femoral pores, as well as the transverse lamelle 
seen on the feet of Anolis, seem to be tolerably constant and consequently 
valuable in classification. These should be combined with osteological 
and other characters carefully used, and also taken with a diligent study 
of the animal’s habits, and thus in time we may hope to get a valuable 
and permanent arrangement. Until such a redistribution can be made, — 
ve 
