160 BULLETIN 15 4, UNITED STATES NATIONAL MUSEUM 



oanoloisua is small and has the general ventral coloration of young 

 " melanostethus " the gular region is blue-black and the chest a shade 

 darker. The dorsal pattern includes many light and dark reticula- 

 tions and spots, without traces of lines, except in a few places where 

 there is a longitudinal arrangement of the dorsal markings. 



It must be admitted that the type is relatively small for so ad- 

 vanced a degree of tessellation, just as are all examples of the insular 

 subspecies, marti/o'is and canus, which are here being recognized as 

 distinct. The diagnostic feature of the latter forms, degree of 

 melanism, is not constant in the three specimens of varhlosus, the 

 type and two examples from Lerdo in Nuevo Leon (F.M.N.H. No. 

 1401), for two are light like cconus and one is dark like maHyris. 

 The difference between the Lower Californian martyris and canus, 

 and this Mexican varloJosus, is very slight, and is apparently only 

 a matter of relative coarseness of the dorsal reticulations, which are 

 never extremely fine in the latter form. In view of this, if the 

 striped Mexican examples of tesselJatus (called aethiops by Cope, 

 see below) were universally converted into the vanolosus type in 

 the intervening Sonora, and if all of the northern specimens were 

 striped, it would be necessary to consider these southern variants 

 as a valid geographical race of tessellatus. But, since the type of 

 differentiation shown has no geographic constancy and appears in 

 fact to represent but a mere variation in the general population of 

 tesscllatih^, variolostis can not be maintained as a distinct taxonomic 

 entity. Martyris and cmius, however, appear to be constantly 

 differentiated island types in coloration, although but slightly varied 

 from tessellatus. Considered by themselves, these insular types are 

 sufficiently differentiated from each other. They show an extreme 

 development in the fineness of their tessellations that is not reached, 

 and is indeed seldom even approached, in tessellatus. Yet future 

 specimens, particularly from northern and central Mexico, may 

 make it impossible to use the diagnoses given here for these island 

 subspecies, and it seems very unlikely that better ones will be found. 



From Hermosillo, Sonora, Cope (1900, p. 582) described his C. 

 tessellatus aethiops. There Avere six cotypes, and one of these, the 

 smallest, is perjjlexus. The latter is mentioned in the original de- 

 scription as "A smaller and probably young specimen which never- 

 theless contains two eggs." It is also the one that was " distinctly 

 striped." The remaining remarks on aetldops refer to the other five 

 specimens. 



According to Cope's description, " G . tessellatus aethiops most re- 

 sembles melanostethus, but the coloration is different in several re- 

 spects. The uniform black color of the adults is unknown in the 

 latter, and the striping of the legs, especially of the hind legs in 

 the adult, is equally a peculiarity of the present form. The posses- 



