1901.] NATURAL SCIENCES OF PIIILADELPIIIA. 91 



TRIMORPHODON Cope. 



Proc. Acad. Phila.. 1861, 297 ; I. c, 678, ami Rep. Nat. Mus., 1101 ; 

 Boul., I. c, III. 53. 



Posterior maxillary teeth elongated, grooved and separated by au 

 interval; anterior teeth elongated; 2 loreals; 1 or 2 preoculars ; 2 

 interuasals; 2 nasals; pupil vertical; scales smooth, with pits, in 

 21-27 rows; anal divided; size medium. 



Hab. — North America and JNIexico. 



Trimorphodon lyrophanes Cope. 



I. c, 297 ; I. c, 679, and Rep. Nat. Mus., 1102 ; Boul., I. c, III, 56. 



Seven maxillaiy teeth; head distinct; head plates normal; 2 

 loreals, one in front of the other; 2 preoculars, usually a small 

 subocular; 3 post-oculars; labials 9; scales in 21 rows; veutrals 

 236; subcaudals 70. Length 710 mm. (tail 110). 



Light gray; deep brown spots, in pairs, on the back (21 pairs iu 

 the type specimen); an irregular series of lateral spots; belly 

 white, with small dark spots on the ends of some ventrals; head 

 light gray, banded with darker. 



Hab. — Arizona and Lower California. 



SIBON Fitzinger. 



Neue Class Rapt., 29 (1826) ; Cope, I. c, 670, aufi Rep. Nat. Mus., 1106; 

 Leptodira (part) Boul., I. c, III, 88. 



Posterior maxillary teeth elongated, grooved and separated by 

 an interspace; 1 loreal; 1 to 3 preoculars; 2 nasals; 2 iuternasals; 

 pupil vertical; scales smooth, with pits, in 19-25 rows; anal 

 divided; size moderate. 



Hab. — North and South America. 



Cope appears to be justified in separating the American species 

 with divided anal, from the Asiatic with single anal; Leptodira 

 Gunther having included both, au arrangement which is followed 

 by Boulenger. 



Sibon septentrionalis Kennicott. 



Dipsas septentrionalis Kenn.. U. S. Mex. Bound. Surv., II, 16, PI. 8, 

 fig. I ; Sibon septentrionale Cope, I. c, 678, and Rep. Nat. Mus., 

 1107 ; Leptodira septentrionalis Boul., I. c, III, 93. 



Head very distinct; body tapering; head scales normal; 3 

 preoculars, the lower one very small; pcst-oculars 2; temporals 

 1-2; labials 8; scales in 21-23 rows; ventrals 194; subcaudals 

 "65-72. Length 750 mm. (tail about one-fifth). 



