41 



PityopTiis hellona, Bd. & GiR., Cat. N. Amer. Kept., 1853, 66, 157.— Kekn., ajjuci Bd., P. 

 R. E. Rep., X, 1859, Williamson's Route, Reptiles, 42,— Bd., P. R. R. Rep., x, 

 1859, Beckwith^s Route, Reptiles, 19. — Kenn., apud Bd., U. S. & Mex. Bound. 

 Sarv., ii, pt. ii, 1859, Reptiles, 19.— Cope, Proc. Acad. Nat. Sci. Phila., 1866, 

 305. — Allen, Proc. Boston Soc. Nat. Hist., xvii, 1874,69.. 



Locality : Saint Martin's Island, Pacific coast of Lower California. In 

 our specimen, there is but one anterior orbital on a side ; postorbitals 

 three. On the left side, there are two prefrontals ; the adventitious one 

 is quite small, and is situated at the inner edge of the larger and nor- 

 mal prefrontal plate of the same side, between the rostral and the left 

 internal postfrontal. Nine superior labials dn each side, the eye resting 

 on the fifth. In those cases where there are but eight labials on a side, 

 the eye always rests on the fourth, and invariably on the fifth when 

 nine plates are present. The additional plate is inserted anterior to the 

 position of the eye ; and in those cases the head is more elongate. 



The ^hole of this small collection of reptiles, with two exceptions, 

 came from the outlying islands along the coasts of the peninsula of Lower 

 California. They can be arranged into two groups, representing, one 

 the Pacific, and the other the gulf islands, accordingly as they are related 

 to the two regions north of them ; namely, the Pacific and Sonoran : 



I. Types purely Sonoran, including all those that came from the gulf 



region : 



Plirynosoma hernandezi. ■ 



Sauromalus ater. 



Crotalus pyrrhus. 



JElaps euryxantlms. 



II. Types purely Pacific, or species belonging as well to the Pacific 

 as to the Sonoran region, including all those that came from the Pacific 

 coast : ' 



Syla regilla. 



Uta stanshuriana. 



Crotalus adamanteus atrox. 



Pltyopliis sayi hellona. 

 I desire especially to direct attention to the occurrence on Angel Isl- 

 and of two highly characteristic Arizonian reptiles, the Sauromalus ater 

 and Crotalus pyrrhus. These have heretofore been confined to Arizona, 

 and they are by no means common there. The naturalists of Wheeler's 

 Survey have explored the Southwestern Territories for three successive 



