1913.] NATURAL SCIENCES OF PHILADELPHIA. 507 



chill shields, which are of about the .same length as the posterior 

 pair. 



"Anteriorly the back is crossed by black bars about 4 scales broad, 

 which are imperfectly continued on the sides of the belly and mostly 

 interrupted on the median line. Toward the middle of the body 

 the lateral parts of the bars tend to become displaced to form a 

 pattern of alternating blotches, which are sometimes connected on 

 the lower part of the sides. Near the tail the black markings are 

 again united into cross bars and on the tail again broken up into 

 alternating spots. The interspaces are about 3 scales wide, and 

 scales are mostly pale (reddish in life?) , relieved by small pale brown 

 lines or spots and generally a poorly defined dark brown spot or line. 

 There is an irregular light collar, from which a poorly defined con- 

 tinuation extends on the temple. Sides of head with pale mark; 

 chin much spotted with black. 



"It will be noted that the characters of this snake are not exactly 

 the same as those ascribed to the genus Drepanodon. The principal 

 differences from the other species are the slightly greater number 

 of maxillary teeth and the shape of the body, but the writer believes 

 that the forms have enough in common to make it advisable to refer 

 the species tentatively to this genus." 



The collection also contains a single paratj^je of this species. 



Named for Dr. George F. Eaton, who, with Mr. Erdis, collected 

 these specimens. 



Lachesis lanceolatus (Lac^pede). 



Lac^pede, Serp., 2, 1789, pp. 80, 121, pi. 5. fig. 1. 

 Boulenger, Cat. Sn. B. M., 3, 1896, p. 535. 



Two t\T)ical examples of this dangerous and wide-ranging species. 



Explanation of the Plate XVII. 



Fig. 1. — Dorsal view of head of type of Drepanodon eatonii Ruthven. Four 



times natural size. 

 Fig. 2. — Lateral view of head of same specimen. Similar enlargement. 

 Fig. 3. — Dorsal view of head of type of Drepanodon erdisii Barbour. Four 



times natural size. 

 Fig. 4. — Lateral view of head of same specimen. Similar enlargement. 



