THE REPTILES 



Blue-bellied Lizards. Sceloporus occidentalis Baird and Girard^*^ 



Field characters. — Of typical lizard form. Tail (when not injured) slightly more 

 than length of head and body. (See pi. 57b.) Scales on upper surface, and sides of 

 body and tail, with conspicuous ridges or 'keels'; 51 or fewer scales in longitudinal 

 row from back of head to line across back of thighs; scales on back of thigh keeled. 

 General coloration above dark brownish or blackish, patterned with lengthwise rows of 

 spots of blackish brown; under surface of body (especially in males) with more or less 

 deep blue. Head and body 3 to 3% inches; tail 3l^ to 5 inches in adult males. 



Occurrence. — Common almost throughout the region. Forage on trunks of trees, on 

 fences, or on rocks.^o 



The Blue-bellied Lizard is perhaps the best known of the typical lizards 

 here in the west, being common througrhout the settled districts of Cali- 

 fornia, where it is known as the fence lizard. The two common names 

 of the reptile just given refer respectively to the blue color on the under 

 surface of the body in the male and to the animal's habit of coming out 

 on rail fences and on similar above-ground structures upon which it can 

 climb about and hunt for insects. 



40 Three subspecies of Blue-bellied Lizard live in different parts of the Yosemite 

 region. Their general appearance is much the same, especially as compared with other 

 lizards in the region, and but little is known concerning their life histories. For these 

 reasons the three are treated together. The characters given below apply particularly 

 to adult males, which sex may be distinguished by the presence of two enlarged plates 

 on the under side of the tail behind the anal opening. 



Western Fence Lizard, Sceloporus occidentalis occidentalis Baird and Girard, the 

 form which inhabits the northwestern half of California, is to be found in the western 

 part of the Yosemite section, where it occurs from Snelling and Pleasant Valley eastward 

 to, and including, Yosemite Valley. It may be distinguished by the greater amount of 

 light color on the under surface of the hind limbs, on the chest, and between the dark 

 patches on the belly. Also the blue patch on the throat is divided, as a rule, not solid. 

 This and the following subspecies are ordinarily to be seen on tree trunks, fences, logs, 

 and boulders. 



Pacific Blue-bellied Lizard, Sceloporus occidentalis bi-seriatus Hallowell, the sub- 

 species common in southern California, reaches the eastern end of the Yosemite section 

 around Mono Lake. Our party took specimens at Mono Lake Post Office. It is char- 

 acterized by somewhat larger size than the preceding and by darker coloration on the 

 under surface. The thighs, middle of belly, and chest are gray or blackish, and the blue 

 patch of the chin is never divided in the mid-line. 



Tenaya Blue-bellied Lizard, Sceloporus occidentalis tai/lori Camp, is a subspecies 

 known at present only from the high country about Merced and Washburn lakes, Tenaya 

 Lake, and Glen Aulin, and from Little Yosemite Valley. It is recognizable at once i)y 

 its solidly bluish black under surface and dark back (without conspicuous spotting). 

 The highest station of observation, on the ridges above Merced Lake toward Mount 

 Clark, was 8800 feet in altitude. This subspecies is to bo seen chiefly on sunlit granite 

 boulders. 



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