152 MR. R. COLLETT ON ECHIDNA ACANTHION. [Feb. 3, 



p. 155). How far this fact is the rule, or whether it is attributable 

 to the younger age of the male, can only be ascertained on the 

 examination of more abundant materials. 



Size. — The largest specimens are a male and a female with a total 

 length of 448 millim. each, and these appear to be full-grown. 

 The second male (No. 5) is younger, with a total length of 415 

 millim., and the skeleton showed that it was not yet full-grown. 

 The third male (No. 1) was young. The females have a total length 

 of 405 to about 440 millim. 



The greater number of the specimens have thus a length of more than 

 16, but not quite 18 inches, which may perhaps be considered to be 

 the normal size, as the generative organs of one of the females, which 

 have been preserved, showed the specimen to be fully developed. 



It is, however, probable that E. acanthion attains a still larger 

 size, as it can be seen by comparison of two skeletons of the same 

 size of E. acanthion and E. aculeata (total length 425 mm.) that 

 the last species is already in every respect fully ossified without a 

 trace of the open sutures, while in E. acanthion, on the other hand, 

 there are still some traces of these earlier stages. It may therefore 

 be concluded, that perhaps the North-Queensland species attains 

 still larger dimensions than E. aculeata \ 



The Covering of the Skin. — The dorsal spines are long and powerful, 

 closely placed, and perfectly hiding the scarce and short fur at their 

 bases. A number of spines are stronger than the others, and are 

 regularly distributed over the back, making it almost possible to 

 arrange them here in three to four irregular series ; they are also 

 distinguishable from the others by the clearer colour of their exposed 

 parts. These strong spines reach a length on the back of 43- 

 47 millim., on the tail sometimes of 55 millim. ; their diameter is 

 3^ millim. 



The other spines, which are far the greatest in number, are shorter 

 and finer, have a length of about 22-30 millim., sometimes a little 

 more, but are distinguishable by their darker colours. Their dia- 

 meter rarely exceeds 2-2^ millim. 



This spiny covering extends forward to beyond the ear, on the 

 sides of the body as far as to the margin of the belly ; one or two 

 spines may sometimes reach beyond the margin, but the rule is that 

 the belly is only covered with hairs. 



The fur at the root of the spines is, as mentioned above, very 

 scarce and short, and it is only a rare exception that the tips of one 

 or two hairs are visible between the spines, as in the young male 

 (No. 1). The forehead and throat are covered with flattish bristles, 

 mingled with a few normal hairs, which commence in front of the 

 eye ; these bristles gradually merge behind into short spines, which 

 successively become stronger ; still on the occiput and the nape 

 they are somewhat shorter than those on the back. The legs 

 are covered with similar flattish bristles, particularly on their outer 



1 Of this latter species there is preserved in the University Museum of 

 Cbristiania a mounted specimen with a total length of about 470 to 4S0 millim. 



