248 BULLETIN 17 7, UNITED STATES NATIONAL MUSEUM 



The subdigital lamellae range between 17 and 22 with an 

 average of 19.7. The head scales are remarkably constant with the 

 exception of those on the occiput. The interparietal is usually one- 

 third to one-half the size of the parietals, but sometimes it is two- 

 thirds, and in the young type of rugosus it is fully as large as the 

 parietals. The occipital scale may be either a little larger or a little 

 smaller than the interparietal. 



Color variation in this species is apparent, though certain patterns 

 predominate at certain ages. In the costatus of Hispaniola, when 

 graded according to size, it is noted generally that the larger individuals 

 have the larger splotches of dark color, while the smaller (100 mm. and 

 less) have a much finer spotting as a rule. But this is not inevitably 

 the case, for No. 59086 (107 mm.) has rather heavy blotches for its 

 size. The markings of the smaller lizards consist of chevron-shaped 

 narrow dorsal bands (about 12 to 16 between axilla and groin), which 

 are continued down the sides, becoming darker and broader and being 

 greatly emphasized by occasional white scales, which appear on the 

 posterior margin there. From the shoulder to the eye there is a broad 

 brown stripe punctuated by vertical white bars (about four between 

 arm and ear) or white spots, and as these become less distinctly joined 

 on the sides they make the lateral continuation of the dorsal chevrons 

 as described. 



A trace of longitudinal marking becomes first evident on the nuchal 

 region, where two dark parallel stripes appear, fading out in the young 

 between the shoulders. 



In larger specimens the chevrons wholly disappear, the only remain- 

 ing traces being the squarish large dark blotches, which are the thick- 

 ened remains of the original chevron end. The nuchal lines have 

 lengthened down the back and broadened greatly, extending even on 

 to the tail in some individuals, while in others the alternating (or 

 opposite) blotches meet at the center of the back. The pattern of the 

 sides does not change much, except that the stripe on the side of the 

 head tends to acquire a central light area. But even in the young 

 this happens also. 



In the two smallest Hispaniolan specimens that I have yet seen, 

 (F.M.N.H. Nos. 13246 and 13247 from Kenskoff, Haiti), measuring 

 42 mm. and 45 mm., respectively, the chevron pattern on the smaller 

 specimen is retained as diagonal series of small dots in the shape of 

 chevrons on the back and tail, while the nuchal lines are suggested by 

 a heavier longitudinal series of spots. The larger specimen is much less 

 spotted in appearance, the diagonal series of dots having almost en- 

 tirely disappeared except for a single longitudinal row of dots, which 

 continues down each side of the back from the nuchal markings, which 

 appear more definitely as lines in this specimen, owing apparently to 

 the fusion of the heavier spots. 



