182 ON THE VARIATION OF THE PIT-VIPER. 



variety are of the spotted type, described as Type III., consisting 

 of three longitudinal series of subequal and alternating dark spots, 

 moi-e or less uniformly distributed on a lighter ground-colour ; 

 the scales are usually of the low, long-keeled type. In the 

 modified form from Venezuela, Berbice, and Peru the spots of 

 group A are darker than those of group B, the whole pattern 

 thus having a less even appearance. In some cases the mai-kings 

 are very indistinct, only the principal spots of group A (A 1, 1, 

 2, 3) being discernible. The scales may be of either type. 



Form 4, L. atrox, vsiV. janiracussa, is the distinct colour variety, 

 which Lacerda regarded as a valid species in 1884, and which is 

 still maintaind as such by Dr. V. Brazil. There is, however, no 

 difference between the Jararacussu and L. atro.v except that of 

 colour and markings. 



The Jararacussu inhabits Brazil, Sao Paulo, and Rio, and is 

 distinguished from the preceding forms by its peculiar markings 

 described above as Type IV., and the fact that the interspaces in 

 the black areas are bright yellow instead of the brown, grey, or 

 olive shades of all the other varieties. The pattern appears to 

 consist of transverse yellow forks issuing from the yellov/ ventrals, 

 which are blotched with black. The tail is black. The head of 

 the Jararacussu is extremely chai'acteristic, the dorsal surface 

 being of a uniform black, from which the black post-ocular 

 streaks are separated by a narrow streak of yellow, continued 

 obliquely from the yellow tliroat. A coloured plate of this variety 

 is given in Dr. Brazil's ' Defense contre I'Ophidisme' (2nd edition), 

 pi. 14, under the name of Lachesis jararacussu. It is also 

 represented in Jan's Iconographie, 47me livr., pi. ii. fig. 3, as 

 Bothrops atrox. 



