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BULLETIN 177, UNITED STATES NATIONAL MUSEUM 



paired median series of rather rectangular, somewhat enlarged scales 

 on the snout from the rostral to the juncture of the supraorbital 

 semicircles, which are closely in contact with each other but with a 

 few small scales interpolated here and there between them and be- 

 tween the paired median series on the snout also; occipital as large 

 as ear opening, triangular in shape, very prominent, with a somewhat 

 smaller but equally noticeable preoccipital in contact with the supra- 

 orbital semicircles and completely filling the area between them and 

 the occipital: the extreme outer points of the occipital narrowly in 

 contact with the posterior part of the supraorbital semicircles: 

 supraocular disk composed of seven or eight polygonal smooth scales. 



Figure 46. — Variations in head shields of i s'r.p'.e populatic: 

 from San Michel da Nord,HakL \.U.5.N.M. Nos. 74451, "445. : . "444;. 7447 ",," : 



incompletely separated from the semicircles by a row of granular 

 scales; one comparatively large shield bordering the inner anterior 

 edge of the first superciliary and surrounded by the supraocular 

 granules: canthus rostralis only moderately developed, the four en- 

 larged scales that distinguish it having a comparatively low median 

 ridge not projecting over the loreal region: superciliary ridge indis- 

 tinctly continuous with the scales of the canthus rostralis, composed 

 of one very elongate and sharply keeled scale followed by a double 

 series of small but differentiated tubercular scales, the anterior of 

 which are separated from the supraocular disk by about four or five 

 rows of granules; loreal rows four: scales of the subocular semicircle 



