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Show 1906.] IN MEXICAN LIZARDS. 283 oblique to their main axis. Cope and others have employed the relative length of the hind limb as expressed by the point which the longest adpressed toe reaches on the neck, ear, or eye. This criterion had to be discarded on account of astonishing variation in allied individuals. Text-fig. 64. Lepidosis of the collar and throat. A = C. tessellatus from El Paso, Field Columb. Mus. Collar composed entirely of small, mostly granular scales. B = C. mexicanus, from Totolapan No. 2. C = (7. communis australis, Cuicatlan, 140 m m . T)~C. communis australis, Laguna. Collar composed entirely of large scales. The skin of the back is granular, but the grains may be fine or coarse ; there is no way of expressing this intelligibly ; moreover, counting of the grains across the middle of the body reveals enormous individual differences-for instance, in C. guttatus of Aqua fria from 100-180 granules across. The arrangement of the scaling of the preanal region proved likewise unmanageable. It does not follow that these discarded characters are of no systematic value. On the contrary, the sum |