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Show 1890.] THE SECONDARY SEXUAL CHARACTERS IN HOMOPUS. 521 5. Note on the Secondary Sexual Characters in the South- African Tortoises of the Genus Homopus. By G. A. BOULENGER. [Eeceived June 9, 1890.] I owe to the kindness of Mr. J. M. Leslie, F.Z.S., of Port Elizabeth, two fully adult living specimens of Homopus areolatus, male and female, which I have the pleasure of exhibiting before the meeting. They were sent to me in illustration of the fact that the male is armed on the back of the thighs with a bony tubercle, which I stated, on the evidence of the specimens in the British Museum, to be absent in that species. The tubercle is, however, comparatively small and rounded, not conical, very much less developed than in H. femoralis and H. signatus ; it is to be found, but in a quite rudimentary condition, in the female from Port Elizabeth. It may be well, on this occasion, to point out the very marked external characters which distinguish the fully adult male:-First, the size of the head, which is much greater, as may be seen from the measurements given below. Second, the shape of the snout; the beak ends in a much stronger point, and its profile descends slightly forwards, whereas in the female the profile slants in the opposite direction. Third, the much greater length of the mandibular symphysis, which measures nearly half the total length of the mandible, as against about one third in the female. Fourth, the greater size of the large detached scale on the inner side of the elbow. And lastly, in this specimen, but not in the others I have hitherto examined, the presence, on the upper side of the tail near its end, of a small bony tubercle similar to that on the hinder side of the thighs. The plastron shows no concavity whatever. On comparing this male specimen with specimens of the same sex of H. femoralis and H. signatus, I find that it differs from them in the following points, apart from the characters which I have given in the Catalogue of Cheloniaus :-From H. femoralis in the much longer mandibular symphysis (see measurements below) and the much smaller size of the femoral tubercle; from //. signatus in both the above characters and in the absence of a plastral concavity, which is well marked in the male of that species. Measurements, in millimetres. Length of carapace Length of plastron Length of head Width of head Length of mandible Length of mandibular symphysis Length of femoral tubercle.... H areolatus. 6- 90 75 23 19 18 8-5 2 ?• 93 84 20 17 14 H. femoralis. 6". 82 74 19 15 13 2- 128 115 23 18 18 6 6 H. signatus. 6- 83 70 20 15 14 5 3 2- 68 61 14 11 11 3 2-5 |
