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Show 1905.] OF THE YELLOW-THROATED LIZARD. 257 position of Gerrhosciurus, that this lizard agrees absolutely and in every detail, so far as the jugal ligament is concerned, with the skink Eumeces. The final stage in the arrangement of the jugal ligament is shown in Physignathus. In this lizard the ligament is attached firmly to the bones at either extremity, and has entirely lost its presumably original connection with the skin. Moreover, in the last-named lizard, the ligament is divisible into two regions. There is, first of all, a stronger narrow ligament which occupies exactly the position of the bony quadrato-jugal bar in Hcitteria, and above this and in part overlapped by it is a thinner but still stout sheet of ligament which entirely fills up the temporal vacuity. This state of affairs does not exist at all in Gerrhosciurus and Eumeces. It is distinctly suggestive of the complete obliteration of the lower temporal vacuity in certain Vertebrates. In view of the fact that bones in some cases can be shown to degenerate into ligaments, it is not certain that the stages sketched out above may not be read in the inverse order. For example, the lower part of the fibula is ligamentous in Birds; but it is not to be assumed that here there is anything but a degeneration of the bone into ligament. The facts which have been detailed above concerning certain Lizards do not, however, appear to me to point to a reduction from a state of affairs such as is found in Hatteria. If we were only acquainted with the condition observable in Physignathus and Iguana, such a view might indeed be held. The bone, it would be urged, has degenerated into ligament in the one case, and has finally disappeared in the other. But the conditions to be seen in Gerrhosci urus and in Eumeces would seem to negative such a supposition. Peritoneal Folds and Coelom. Although the suspension of the alimentary tract and the other viscera contained in the coelom is broadly like that of many other Lacertilia, there are some differences of detail which require attention. In the female example the line of attachment of the oviducal membrane, which diverges laterally 011 each side, marks oft sharply the posterior pigmented area of the coelomic membrane from the anterior non-pigmented or less pigmented area. This is quite a common and well-known arrangement among the Lacertilia. The reason why I bring the matter forward here, is that Gerrhosciurus differs from Eumeces, where there is no such differentiation of pigmented and non-pigmented areas ^, and because the pig* This is not however, a distinctive mark o f difference from the Scincidae and of likeness to Lacerta. Lacerta shows this sharp demarcation; but there are varying decrees amon°- the Scincida. In Eumeces there is hardly any pigmentation; 111 Tiliaua scincoides there is a moderate amount, but evenly spread through the body-cavitv (in a male) In Macroscincus cocteaui (female), however, the oviducal membrane marks off two areas; but the posterior area is not so deeply pigmented as in Gerrhosciurus. P ro c . Z ool. S o c .- 1905, V o l . II. No. XVII. 17 |