OCR Text |
Show 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 1. 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 diameter 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 tbis latter species tbere is preserved in the University Museum of Obristiania a mounted specimen with a total lengtb of about 470 to 480 millim. |