1894.] NATURAL, SCIENCES OF PHILADELPHIA. 425 



section is an oblique membranous Hounce with a lobate margin. 

 No tracheal lung ; and I could find no right lung. 



Amphiesma stolatum L. 



In this species the hemipenis displays the usual natricine charac- 

 ters of a basal hook, and small spines reaching to the apex, without 

 ruches or flounces. The spines are, however, coarser than in most 

 other species. The organ, moreover, is undivided, and with un- 

 divided sulcus, and as A. stolatum is the type of the genus, the 

 latter must be defined accordingly, and not as divided, as I inferred 

 from an examination of allied species which have been referred to 

 it by authors.' These supposed species of Amphiesma which I have 

 examined, which have divided hemipenis and diacranterian denti- 

 tion, are also characterized by the presence of fossje of the hemipenis 

 from the center of each of which a spiuule issues. These are the 

 Amph. figrinum and A. ceylonense, and they belong to my genus 

 Bothrodytes, which name should take the place of Amphiesma in ray 

 original Prodromus, 1. c. The genera of Natricinse with basal hooks 

 will then be as follows : — 



I. Fusiform types ; hemipenis and sulcus undivided. 

 Hemipenis simple ; anal divided ; 



One internasal, scales keeled ; Haldea B. & G. 



Two interuasals, scales keeled; Amphiardis Cope. 



Two internasals, scales smooth ; Virginia B. & G. 



Hemipenis with two apical papilhc; anal entire. 



Two internasals; scales keeled; Tropidodoninm Cope. 



II. Colubriform types. 



a. Hemipenis undivided. 



b. Dentition syucranteriau or isodont. 

 Anal plate entire; a loreal; Eutaniia B. & G. 



Anal plate divided; no loreal; Storeria B. & G. 



Anal plate divided; a loreal; Natrix Laur. 



Anal plate divided; a loreal; one prefrontal; Trimerodytes Cope 



bb. Dentition diacranterian. 

 Scales keeled; two internasals; Amphiesma D, & B. 



Scales smooth; one internasal ; Liodytes CoTpe. 



aa. Hemipenis divided. 



b. Dentition syncranterian. 



1 American Naturalist, 1893, p. 483. 



