Cope.] 1'^^ [July 16, 



From Cliihuitan, Teliuantepec, Western Mexico. F. Sumichrast, Coll. 

 in Mus. Smithsonian, No. 248. 



Symphimus leucostomus, Co'pe, sp. et gen. nov. 



Char. gen. Dentition isodont ; cephalic plates normal except that the 

 internasals are confluent with the nasal, and the latter with each other 

 and with the loreal. Preorbitals one. "Rostral shield not prominent ; 

 scales smooth, equal, uniporous ; anal bitid. General form elongate. 



This genus differs from Chilomeniscus, to which its technical characters 

 are similar, about as much as any colubrine serpent does from a burrowing 

 calaniarian. Its form is nearly that of Cyclophis, and it should perhaps 

 be placed nearest to it in the system. Steindachner's Bergenia mexicana* 

 should, it appears to me, be referred to Chilomeniscus Cope, of which it 

 is the fourth species. 



Char, specif. The head narrow, not very distinct, the muzzle acumin- 

 ate, but obtuse at the extremity. The scales in fifteen longitudinal 

 series. The form is cylindric and elongate. The tail of medium length 

 as in Cyclophis. Rostral plate high as wide, scarcely visible from above, 

 not prominent. Side shield of the muzzle pierced by the nostril and ex- 

 tending to the preocular ; latter long as high, not reaching the frontal. 

 Postoculars one on one side, two on the other. Superior labials seven, 

 third and fourth bounding orbit, all longer than high except the fifth ; 

 temporals 1-2 large, the anterior bounding the fifth and sixth labials. 

 The median sutures of the rostronasal and prefrontal plates of equal 

 length. Frontal longer than wide, with concave sides ; superciliaries 

 wide, occipitals elongate, common suture nearly as long as prefrontals 

 and frontals together, truncate behind. Inferior labials eight, fifth 

 largest — narrow; pregeneials a little longer than postgeneials. The eye 

 is rather small. Urosteges, 111, gastrosteges. 



Color olive gray above, a dorsal band of light brown extending over 

 three rows of scales to the origin of the tail ; the skin of its median region 

 being yellow. Throat, chin and superior labials light yellow, a black line 

 above the superior labials from the second posteriorly. The brown of the 

 upper regions descends to the lower row of scales at about the twelfth 

 transverse row ; two or three lower rows are pale edged. Belly dirty 

 white. The dorsal band is posteriorly ill defined, and extends a little be- 

 yond the vent ; tail brown. 



In. Lin. 



Total length, No. 240 31 5.5 



Length tail 10 9 



Length rictus, No. 227 6.8 



Interorbital width 2.8 



Width muzzle 1.8 



AVidth orbit 1.4 



Length tail 7 



No. 340. From Chihuitan, from the same. 



No. 227. From the collections of the Smithsonian Institution from the 

 province of Oaxaca, Mexico, made by Francis Sumichrast. 



* Reised. Oester. Freg. Novara Eeptilia, 92 fig. 



