CROCODILIANS, LIZARDS, AND SNAKES. 



1017 



III. Second row of scales keeled; orbit bounded below by a siugle labial. 

 * Scales in 21 rows; superior l.ibinls eight. 



1. Temporals, 1-3. 



Oculars, ."-S ; labials longer than high; loreal longer than high; rostral 

 subtriaugnlar ; muzzle narrow; seven rows of spots, no stripes. 



E. multimacitlata CoTpe. 



Like the last; but rostral a transverse oval with free borders; loreal 



nearly entering orbit, and labials narrower. . E. rnfopuiictdta Cope. 



IV. Second row of scales smooth like the first; others with weak keels. Orbit 



T»orderod l)y two labials. 

 ' Scales in lit rows; superior labials eight. 

 1. Temporals, 1-2. 



Oculars, 2-3; loreal longer than high; head little distinct; dusky stripes 

 wanting or indistinct E. meJanogasief Wiegmann. 



The affinities of these vspecies may be expressed in the following 

 diagram : 



Angustirostris Nigrilatus 



Macrostemma 



Sackenii Saurita 



Proxima 



SUMICHRASTII 



Meg A LOPS 



Cyrtopsis- Chrysqcephala 



Leptocephala 



PULCHRILATUS ScALARIS 



The E. sirtalis present.s the greatest number of points of contact with 

 other species. It also inhabits the region of geological]}^ the greatest 

 age, or that region which lias been a frog land area for the longest 

 time. Although large portions of the west of Xorth America were ele- 

 vated at the close of the Cretaceous period, and probably before the 

 genus Eutwnia was in existence, the ancestors of Eutcenia may be 

 safely believed to have inhabited the area which was land prior to the 

 Cretaceons. so that the descent of Eutwnia was new and possibly in the 

 eastern rather than in the western half of the continent. It is thus 

 rendered probable that Eutivnia sirtalis is the ancestral form. This is 

 also conlirmed by the fact that it is a spotted .species, since the unicolor 

 species, as E. saurita, have spotted young. 



