1885.] MR. O. THOMAS ON THE RACES OF ECHIDNA. 331 



Commencing with the external characters, the first thing to be 

 noticed is the extraordinary difference between the Tasmanian and 

 the northern races in the relative development of the spines and the 

 hairs on the back. The extremes are indeed much further apart than 

 one would ever expect to occur within the limits of a single species, 

 but these extremes grade into each other on the examination of a 

 large series. 



In the true E. aculeata of New South "Wales we find that average 

 specimens are covered with a thick coating of long stout spines, from 

 35 to 60 millim. in length, with a very sparse and thin undergrowth 

 of hair, visible only upon separating the spines, and quite hidden in 

 the ordinary position of the animal. The head, belly, and legs are 

 covered with a mixture, in about equal proportions, of flattened 

 semi-spinous bristles, and of thin, more or less woolly, hairs. Passing 

 northwards, we find that in Queensland specimens {E. acanthion) the 

 hairs of the back are still more reduced as compared to the spines, 

 and that on the belly the flattened bristles tend entirely to supersede 

 the hairs, a tendency carried out completely in E. lawesi, where, 

 except in the neighbourhood of the pouch, the belly-hairs are 

 entirely suppressed, and the head and underside are evenly though 

 thinly covered with bristles only. On the other hand, probably 

 owing to the moister climate of New Guinea, the hairs on the back 

 somewhat reassert themselves at the expense of the spines, being in 

 specimen a decidedly more visible than in average aculeata, and in 

 h nearly as prominent as in setosa, the spines in both being reduced 

 to from 20 to 35 millim. in length. 



Going now southwards from New South Wales, we find that the 

 hair, as compared on the back with the spines, and on the belly with 

 the bristles, rapidly gains the upper hand, until in Tasmanian 

 specimens the spines, especially along the middle of the back, are 

 almost entirely hidden, and the bristles below suppressed, both upper 

 and under sides being clothed with thick woolly hair, some 20 

 millim. in length, a state of things obviously resulting from the 

 moister and colder climate of Tasmania. There is also a good deal 

 of variation in specimens from the same localities, probably owing to 

 seasonal change ; but as I have no dated specimens available, I am 

 unable to speak definitely on this point. 



But as to the specific value of this hair-development, we soon find, 

 on looking through a large series, that there are specimens which do 

 not conform to the general rule as to locality; thus specimen/ from 

 South Queensland, the centre of the aculeata range, has its hairy 

 covering developed almost precisely as in average Tasmanian indivi- 

 duals. Again, the fact that the New-Guinea Echidna, coming from 

 a moist though hot climate, should tend to resemble the Tasmanian 

 race in the length of the hair and shortness of the spines on the back, 

 is alone strongly confirmatory of my view that the greater or less 

 development of the hairs is a character so directly climatic, and so 

 easily affected in different localities by a greater or less degree of wet 

 and cold, that it cannot be taken as indicating real specific distinction. 



The colour of the Echidna varies somewhat owing to the relative 



