OCR Text |
Show 1906.] IN MEXICAN LIZARDS. 321 of the transverse rows often decrease more rapidly towards the sides, especially in C. guttatus. One or twTo rows of granules at the posterior border of the collar are perhaps more frequent in C. guttatus and C. immutabilis than in C. deppei. Throat (text-fig. 65 A).-In perhaps the majority of C. immutabilis the scales on the centre of the throat are somewhat enlarged so as to form a conspicuous cluster, but there are many in which such a cluster is ill-defined, or absent, regardless of age, sex, and locality. Front of humerus protected by scales which vary much in size and in numbers. The size decreases from the anterior or outer margin backwards. Sometimes there are only 3 rows of distinctly enlarged scales, followed by much smaller scales which are continued upon and slightly beyond the back of the elbow ; or there are 4, 5, 6, or even 7 rows of larger scales, and in these latter cases most of the scales are of medium size. Sometimes there is a break, filled by granules, between the anterior larger scales and those on the posterior side above the elbow, which in such cases form a little cluster or nest. Such a nest occurs in Atlantic and in Western specimens. Otherwise the Atlantic specimens seem to be remarkable for possessing only 3 enlarged rows. Posterior side of forearm (text-fig. 62 A).-There are no post-antebrachial plates. Almost universally, without exception in the Atlantic specimens, the posterior surface from elbow to wrist is covered evenly with small granules. Anterior side of forearm.-Mostly with 1\, sometimes with 3, longitudinal rows of transversely broadened plates, very variable in detail. Anterior side of femur.-The number of longitudinal rows of scales and plates, between the granules of the dorsal surface and the row of femoral pores, is considerable, about 10 to 12. One row is always distinctly larger than the rest. Including this row, and counting thence to the pores, across the thickest part of the thigh, there are from 7 to 10 rows, mostly 8 or 9. Only in rare cases are all these rows regular; frequently one or more rows are very incomplete, being represented by a few irregularly intercalated scales. The smallest number of rows, wavering about 7 (in one case with even this number imperfect), I have found in the five specimens from and near San Luis; these specimens are in other respects not at all aberrant, but rather typical C. immutabilis. In an adult male from Agua fria are only 7 rows on the left, and 8 very incomplete rows on the right thigh ; in another specimen 8 complete right and 9 complete left rows. Whilst in C. deppei usually the three biggest vows, rarely only two, reach down to the knee, in C. guttatus + immutabilis even the biggest row does but rarely extend to the bend of the knee. Inner aspect of tibia protected mostly by 3, often by 1\, exceptionally only by 2 rows of large plates. The preanal cluster of plates and scales is separated from the ventrals by a rather long and narrow isthmus which is covered |