VARIATION OP THE PIT-VIPER. 



181 



characteristic chevron, or triangle, which, however, varies slightly 

 according to localities. 



The most primitive type of marking is not fotmd in the 

 W. Indies proper, or south of Colombia and the Gnianas, but 

 prevails north as far as Mexico, and appears to be constant in 

 Trinidad. Specimens of this form have scales with the high short 

 keel. In the W. Indies proper a less primitive variation occurs, 

 in which the elemental spots are more confluent and the pattern 

 less distinct ; the scales may either be of the short high-keeled 

 or long low-keeled type. As this variety extends southwards 

 the markings, though still undoubtedly of Type I., frequently 

 approach those of the Jararaca, or Jararacussu in type, and the 

 scaling ma}?- conform to either type. Thus the L. atrox and 

 L. lanceolatus of Dr. Vital Brazil, which are marked simply with 

 dark triangles on the sides, undoubtedly approach the Jararaca 

 of Wied in pattern. A pattern of markings intermediate between 

 the primitive, type of this variety and that of the Jararacussu 

 occurs in W. Ecuador. L. atrox, var. affinis, is the most widely 

 ranging of the four varieties (Mexico to Southern Brazil and 

 Peru). All forms of it are marked with triangles or chevrons, 

 with their apex turned towards the mid-dorsal line. Group A is 

 always darker than B, and encloses an area darker than the sur- 

 rounding ground-colour. The ventrals may be uniform cream- 

 colour or yellowish, or blotched or speckled with black. In the 

 young the elemental spots, when present, are more distinct, a 

 certain amount of confluence or fading taking place with age. 



Form 2, L. atrox, var. jararaca, has been considered a distinct 

 species since the time of Wied, but as it does not differ from the 

 typical L. atrox in any appreciable way, save in the dorsal mark- 

 ings, I consider it to be a variety only. The Jararaca inhabits 

 Brazil, and is especially prevalent in Bahia, Sao Paulo, and 

 Bio. It is recognized by its annulated form of markings, pre- 

 viously described as Type II., consisting of dark, darker-edged 

 bands, narrower on the mid-dorsal line than on the sides. These 

 bands are more than their own width apart, the interspaces being 

 lighter and unspotted. The ventrals may be uniform, spotted, or 

 powdered with black. 



Figures of the Jararaca are given in Wied, Abbild. Nat. Bras., 

 under the name of Cophias atrox ; Wagler in Spix, Serp. Bras, 

 pis. xix., xxi., under the names of Bothrops megmra, B. leuco- 

 stigma, B. tessellatus, and B. tamiatus ; and in Jan, Icon. Oph. 

 xlvii. pi. iii. under B. atrox. 



A typical specimen of this variety could not be confounded with 

 the preceding, but in the British Museum collection there are 

 some young specimens from Berbice (Cat. Sn. p. 539, spec, e-*:), 

 which are exactly intermediate between these three varieties. 



Form 3, the typical L. atrox < L. lanceolatus) occurs principally 

 in the West Indies, which is the acknowledged home of the 

 Fer-de-lance, but also in the Guianas, Venezuela, and curiously 

 in Peru, in a somewhat modified form. The markings of this 



