1892.] NATURAL SCIENCES OF PHILADELPHIA, 337 



enable us to reach final conclusions. It is, however, evident that 

 the boundaries of the zoological district of Texas do not extend east 

 of Dallas. 



The only exclusively Texas forms of the above list are the follow- 

 ing : Chorophilus triseriatus clarkii Bd., Kinosternum flavescens^ 

 Ag., Trionyx emoryi Ag., Holbrookia texana Trosch., Phrynosoyna 

 cornutum Harl., Contia episcopa episeojia Kenn., Natrix fasciata 

 transversa Hallow., Crotalophorus catenatiis edivardsii B. & G. ; 

 that is, four species and four subspecies. Species of the Louisianian 

 district: Ophibolus getulus sayi Holbr. and Eutoenia proxima. 

 Species of the Sonoran region and Texan district, three: Bufo dehilis 

 Gird., Crotaphytus collaris Say, Crotalus adamanteus atrox B. & 

 G. Species of the Sonoran entering the list : Cnemidophorus gularis 

 gularis B. & G., Phrynosoma modestum Gird. ; two species. Species 

 of the Central Region are more numerous, viz.; Biifo cognatus Say, 

 Spea hammondii bombljrons Cope, Chrysemys elegans Wied., Hol- 

 brookia maculata B. & G., Pityophis sayi sayi Schl., Heterodon 

 nasicus nasieus B. & G., Crotalus confluentns confluenius Say ; total, 

 three species and four subspecies. Synoptically the results may be 

 tabulated as follows. 



species subspecies 

 Texan, 4 4 



Central, • 4 2 



Texan and one other region, 6 7 



Other species of the list not included in these figures, have a still 

 wider distribution. 



It seems from the above, that the region explored is the meeting 

 ground of species of several different regions, as its geographical 

 position would indicate. 



^ This species may also occur in the Sonoran region. 



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