144 OP HID I A. 



mental shields may be observed extending to the anterior abdominal 

 scutella. There are a few lateral scale-like shields on the throat. 



The neck and body are slender, subcylindrical, a little deeper than 

 wide. The tail is short, conical, and very slender. The scales are 

 subrhomboid, disposed upon fifteen longitudinal series, eight of which 

 may yet be observed upon the base of the tail. Those in the lateral 

 series are but slightly larger than the rest. The abdominal scutellae 

 are narrow, one hundred and eighty in number, the preanal one being 

 large and entire. The subcaudal scutellae are disposed upon a double 

 series, sixty-three in number. 



Dorsal rows fifteen ; abdominal scutellae one hundred and eighty ; 

 subcaudal scutellae sixty-three ; total length nine inches ; tail two 

 inches. 



The upper surface of the head is yellowish-brown, with a black spot 

 upon the external margin of the supraocular plates. A black horse- 

 shoe-like marking exists upon the occipital plates. The posterior two 

 upper labials are almost black; the temporal region is spotted likewise. 

 The upper part of the body is covered with transverse black patches, 

 separated by narrow whitish spaces, giving to the body a semi-annulated 

 appearance. On the posterior half of the body these patches are inter- 

 rupted laterally, and in most instances the divided blotches of the 

 sides alternate with the dorsal one. The abdomen is dull-whitish, 

 laterally maculated, the extremity of which maculae corresponding 

 to the white spaces, which expand on the sides, owing to the narrow- 

 ing of the black patches upon the same region. 



LOG. Found coiled up under a stone, in the Amancaes Valley, 

 near Lima, Peru. 



Plate XI, fig. 11, represents Sibynon nebulatus, size of life. 



Fig. 12, is a profile of the head. 



Fig. 13, an upper view of the same. 



Fig. 14, an under view of the head also. 



Fig. 15, represents the outline of the scales. 



Fig. 16, the vent and adjoining scutellae. 



Figs. 12-16, are magnified about half their diameter. 



