102 IDENTIFICATION. 



then the length of its proximal foot-pad, as described in our notes, 

 will betray it. In short, it is a mouse ; but which of the four ? Are 

 its hind feet brown, white, or grey ? They are grey, so it is the 

 Common Mouse. Are its ears short and broad ? They are long and 

 rounded, again the only alternative is Common Mouse ; and a refer- 

 ence to the further points mentioned in the notes confirms the 

 diagnosis. 



In dealing with the cetaceans the first thing is to see if there 

 are any teeth. If there are none there will be whalebone, and 

 the animal must be one of the six whalebone whales, readily dis- 

 tinguishable from each other by their fins and flippers. If there are 

 teeth only in the lower jaw it will either be Risso's Grampus or one 

 of the four Physeteridse, probably the Bottlenose ; if there are teeth 

 in both jaws it will be one of the dolphin family. Should the beak 

 be long, the species must, as shown by our table, be one of two ; 

 either it is the Bottlenose Dolphin, in which the pairs of teeth total 

 up to twenty-one or less, or else the Common Dolphin, when its 

 pairs of teeth will be forty or more, its jaws will be equal in length, 

 and its palate will be grooved. 



Let our last example be a still commoner cetacean belonging to 

 the beakless group. It is not grey in colour, so it is not the Narwhal; 

 it is not white, and so cannot be the White Whale ; it is not almost 

 entirely black, and so is not the Black Whale. It is black above 

 and white below, almost half and half in fact, but having no white 

 spot over the eye, no particularly tall dorsal fin, and more than a 

 dozen pairs of teeth ; thus it cannot be the Killer, but must be the 

 Porpoise, as its many spatulate teeth sufficiently show. 



An outline sketch of a skull is given with every genus, for the 

 skull is almost as often found as the living animal, and so far as the 

 genus is concerned is as easily distinguishable. The six orders are 

 by it recognisable at a glance ; there is no mistaking the peculiar 

 dentition of the bats and insectivores, the canines and carnassials 

 of the carnivores, and, when the carnassials are absent, the peculiar 

 dental equipment of the seals. The incisors of the rodents are quite 

 as noticeable, the heads of cattle and deer are as well known as those 

 of horses and sheep, and the cetacean skull has a character of its 

 own that cannot be mistaken. In examining a skull look first at the 

 teeth, as regards their number, character, and arrangement, then 

 observe the peculiarities of the lower jawbone and its junction with 

 the squamosal, close to which will be found the auditory bulla or 

 tympanic, and then examine the frontal, particularly as to the 

 absence or presence of the postorbital, that small shelf-like process 

 over the eye which we have found so useful as a guide. 



The most easily recognisable characteristics are mentioned in 

 the notes, which are given mainly fer the purpose of confirming the 

 identification. For further details as to structure, habits, and 

 localities, reference must be made to the many works, more or less 

 technical, in which the animal may not appear under the name 

 herein adopted, but under some other in the following fairly com- 

 plete list of the synonyms of the British mammals in use at various 

 times during the last hundred years. 



