OCR Text |
Show 154 MR. R. COLLETT ON ECHIDNA ACANTHION. [Feb. 3 In a male specimen, with a total length of 448 millim., the skeleton is perfectly ossified. The slcull is very much like that of E. aculeata, but may probably always be distinguished by its narrower cerebral area and propor- Skull of Echidna acanthion, rf. No. 5. tionally short snout, although scarcely different in this respect from the South-Australian and Tasmanian species. The length of the skull in proportion to the total length of the skeleton is as 1 to 4 (3-93 to 4-26). When the skull is seen from behind, the lateral profile, especially in the somewhat younger specimens, widens regularly downwards, the os squamosum having its greatest height below, and the upper part of os temporale (perioficum) diminishes regularly towards the parietalia. The greatest breadth, which is to the length as 1 to 2 5, Fig. 2. Skull of Echidna acanthion, § . No. 9. is therefore in E. acanthion situated at the bottom of the skull, quite near the glenoid fossa. In the perfectly full-grown specimens (male and female) the skull becomes iess narrow upwards, but in all cases does not widen as in |