Length to anus 21 22 24 32 33 35 41 42 Length of tail 14 16 21 23 23 .. 46 27 Width of head 3 3 3¾ 5 4½ 5 5 6 Snout to orbit 1½ 1¼ 1½ 2 2¼ 2 2¼ 2½ Snout to gular fold 5 5 6 7¼ 7 8 8½ 9½ Snout to fore limb 6 6 8 10 9 10 12 12 Between limbs 13 14 15 21 19 23 26 26 Fore limb 4½ 4 5 6¼ 6 6 7¼ 8 Hind limb 4½ 4 5 6½ 6 6¼ 7½ 8 =2. Sceloporus biseriatus becki= _Van Denburgh_. A series of eight _Scelopori_ collected on Santa Rosa Island by Dr. Gustav Eisen in June, 1897, seems to show that the differentiation from _S. biseriatus_ has not progressed so far on this island as on San Miguel.[4] Thus although all the adult specimens from Santa Rosa Island show the coloration of the San Miguel Island form, only two have the typical arrangement of the supraoculars, while the other six specimens have the frontoparietal separated from the enlarged supraoculars. The less highly colored young males show a single median blue throat patch, as in _S. biseriatus_, indicating that the island lizard is more closely related to that species than to _S. occidentalis_. [Footnote 4: Dr. Merriam tells me that a parallel is found in the island foxes, whose characters are constant on San Miguel but not on the other islands.] The fact that the characters of this form seem to be constant on San Miguel while varying toward _S. biseriatus_ on Santa Rosa and Santa Cruz islands raises an interesting question in nomenclature: Should the San Miguel Island form be regarded as a species or as a subspecies? If these lizards inhabited a peninsula one would use a trinomial for them all, but since they are found on well separated islands the facts seem to be best expressed by the nomenclature adopted above. 3. =Gerrhonotus scincicauda= _Skilton_. PLATE VII, FIGS. 3-4. _Gerrhonotus scincicauda_ VAN DENBURGH, Occas. Papers, Cal. Acad. Sci. 5, 1897, p. 106. I am unable to distinguish six specimens (Cal. Acad. Sci. Nos. 3881-3883 and 3896-3898) collected on Santa Rosa Island from the species now known as _G. scincicauda_; that is to say, the form with fourteen longitudinal rows of scales, single interoccipital plate, large azygous prefrontal, longitudinal lines along the middle of each row of ventral scales, and smooth temporals. This clearly is the form to which Baird and Girard applied the name _G. scincicauda_, but that it is the species originally described by Skilton seems far from certain.[5] [Footnote 5: Skilton's description, which seems to apply rather to the species afterward named by Baird and Girard _Gerrhonotus principis_, is as follows: