Santa Rosa Island.
I have examined one species of Batrachoseps and two kinds of lizards from this island. The Gerrhonotus has already been reported from the island, the others are new to its known fauna.
1. Batrachoseps pacificus Cope.
Dr. Gustav Eisen secured eight specimens of Batrachoseps on Santa Rosa Island in June, 1897. These are now in the collection of the Academy (Nos. 3877-3880 and 3891-3894) and seem to differ in no respect from the form found on San Miguel Island. All have seventeen costal grooves.
The measurements of these specimens are
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
| 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.
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]
The specimens from Santa Rosa Island all have dorsals in fourteen longitudinal series. The number of transverse series between the interoccipital plate and the backs of the thighs is fifty in one specimen, fifty-one in three, fifty-two in one, and fifty-three in one. One has the brachial scales very weakly keeled. They were collected by Dr. Gustav Eisen in June, 1897.