Mat, 1893.] REPTILES OF THE DEATH VALLEY EXPEDITION. 179 



clarkii and magister as unconditional synonyms of 8. spinosus, evidently 

 because he found a " want of agreement between the number of pores 

 and the distribution of the species." However, had he first separated 

 clarkii and magister by their proper characters which are not to be 

 found in the number of femoral pores, he could not have missed the 

 agreement looked for. 



I must myself plead guilty of having confounded $'. clarkii and 8. 

 magister, misled, as I was, by the almost unanimous verdict of herpe- 

 tologists. If there was a settled question in regard to the Scelopori, 

 I thought surely to have it in the identity of these two names. I re- 

 garded no identification more secure than that of the specimens col- 

 lected by Dr. Merriam in the Grand Canon of the Colorado as 8. clarkii* 

 As a matter of fact, however, they are 8. magister. 



That I was finally undeceived is principally due to Mr. P. L. Jouy, 

 who, while collecting for the National Museum near Tucson, southern 

 Arizona, in 1891, had the good fortune to observe both species alive. 

 In sending the specimens, he wrote me that he had undoubtedly two 

 species which he could distinguish not only by their color when alive, 

 but also by their habits and the different localities which they fre- 

 quented, one being shy and agile, the other fearless and sluggish; one 

 found only on the mesa and on the ground, the other near the river, 

 and chiefly on trees and bushes. Not being able, upon a cursory ex- 

 amination, to find any tangible character, I wrote back that there was 

 only one big 8celoporus and 8. clarkii was its name. Upon his return, Mr. 

 Jouy again brought up the question, and as he was so very persistent, 

 I promised him to examine all the material carefully, a promise made 

 more to please him than because I expected a different result. I went 

 to work and it just so happened that the first two specimens which I 

 picked up belonged each to a different species. My eye at the very 

 first glance hit upon the most distinctive character which separates the 

 two, viz, the difference in the spiny scales which protect the ante- 

 rior border of the ear opening, a difference which is quite apparent 

 upon an examination of the accompanying figures (PL I, figs. 1 and 2). 

 The constancy of the character was soon verified in a large series of 

 specimens, as well as the concomitancy of the presence or absence of 

 dusky cross markings on the dorsal aspect of the forearm and hand. 



It would have been difficult to ascertain the correct names of the two 

 species from the published descriptions, but the types of both 8. clarkii 

 and 8. magister are still in the collection, and fortunately they belong- 

 respectively to the two species. 



Upon plotting on a map the various localities from which I have 

 examined specimens (about forty), it was shown that the two species 

 inhabit different areas, and that the habitats come together and partly 

 overlap in southeastern Arizona, notably arouud Tucson. But here 



* North American Fauna, No. 3, p. 110. 



