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Show 1905.] ABNORMAL RANID LARV/E. 59 these have been submitted to Mr. G. A. Boulenger, whom I have asked to add a note as to their identity. I need only say that they appear to belong to the genus Rcinci*. My observations are of necessity confined to the external appearance and osteological characters of the abnormal specimens, with a general consideration of their visceral anatomy, for their muscular tissues are too decomposed for proper investigation. Even cartilaginous structures have degenerated greatly. As regards visceral anatomy, the more advanced of the two tadpoles (which I shall call A) has an alimentary canal resembling that of a young frog, well-developed and apparently healthy. The tongue and palate are as in an adult. The lungs are large, extending nearly to the posterior end of the body-cavity; the kidneys seem to be normal, but I cannot trace any part of the generative system. The heart and larger blood-vessels are apparently normal. The condition of the viscera is less advanced in the other specimen (B), in which the mouth is that of a typical Ranid larva, except that there are no horny teeth. The intestine is still coiled in a spiral, and the lungs are small. It is in the structure of the limbs and axial skeleton that the main abnormalities are found in both specimens. Figs. 1 ,1 a , 2, 2 a, of PL VI., show that there is no hind limb in either specimen, and that while the fore limbs are well-developed in A, they can be seen through the skin in B. The dimensions of the two specimens are:- A. B. mm. mm. Total length ............... ............. 78 82 Snout to vent ............... ............. 42 28 (ap. Tail ................................ ............. 35 54 Right arm ................... ............. 30 16 Left arm ....................... ............. 25 17 Before dissecting A, I was led by deceptive appearances to believe that the hind limbs were developed beneath the skin, and I have to thank Mr. G. A. Boulenger for suggesting a further examination, which showed that I had been wrong in this belief. A dissection of the pelvic region led to an examination of the skull and vertebral column of A ; in B I could find very little, owing to the fact that its skeleton had been chiefly cartilaginous. Although the head of A looked like that of a young frog, the lower jaw was quite unossified and soft, and the cranium was in a very simple condition. The cranial box was well ossified above and on the sides, the bone being stout and sculptured on the surface. Its floor was represented by a delicate membrane, through which the remains of the brain could be seen. Below this, but not in close contact with it, lay a large, well-ossified * [They are undoubtedly referable to Rana alticola Blgr., of which larvae arc figured in the Blit. Mus. Catalogue of Batracliia Ecaudata, p. 63.- G. A. B.] |
