618 mr. g. a. boulenger on the 



2. Eryx. 

 Daud. Hist. Kept. vii. p. 251 ; Bouleng Cat. Sn. i. p. 122. 



1. Eryx thebaicus Eeuss, Mas. Senckenb. i. 1834, p. 134; 

 Bouleng. t. c. p. 125. 



Upper Egypt to German East Africa. 



Family Colubrid^. 



Three parallel series : — 



No poison-fangs ; all the teeth solid A. As'lypha. 



Poison-fangs behind B. Opistlioglypha. 



Poison-fangs in front C. Proteroglypha. 



A. Aglypha. 



I. Loreal present (occasionally absent in Homalosoma, recognisable by the com- 

 bination of a single nasal shield, paired snbcaudals, and a low number of 

 ventral shields, 113-144). 

 A. Snout without angular horizontal edge ; internasal and prasfrontal paired. 



1. Scales in 19 rows or more, not oblique ; bodj' not remarkably slender. 

 a. Pupil round. 



a. A single anterior temporal. 



Scales in 19 rows ; anal divided Tropidonotus. 



Scales in 19-25 rows ; anal entire ; a deep groove on side of head, 



above upper labials ; Gli/plioli/cus. 



(i. Two or three superposed anterior temporals. 

 Scales keeled, in 23 rows; a deep pit between nasal and 



prseocular Bothrophtliahnus. 



Scales smooth or ver}' obtusely keeled, in 25 to 31 rows S»enda^pis. 



Scales smooth, in 21 rows Coronella. 



h. Pupil vertically elliptic ; scales smooth, in 23 to 



33 rows Soodon. 



2. Scales in 13 to 17 rows, or, if in 19, extremely narrow and oblique. 



a. Pupil vertically elliptic; snout much flattened; scales in 15 or 17 rows. 



Scales smooth Lycoph idium. 



Scales keeled, vertebrals bicarinate SimocepJialus. 



b. Pupil round ; body usually very slender (tree- snakes). 

 a. Scales in 13 or 15 rows, smooth. 



Subcaudals not keeled Clilorophis. 



Subcaudals keeled and with a notch corresponding to the keel, 



same as on the ventrals I'hilothamnus. 



[3. Scales in 15 rows, keeled. 



Subcaudals keeled and notched Gastropyxis. 



Subcaudals not keeled ; two superposed anterior temporals Hapsidophri/s. 



y. Scales in 17 or 19 rows, very narrow, keeled ; eye very large. 



Lateral scales shorter than dorsals Thrasops. 



Lateral scales as long as dorsals JRJiamnop/iis. 



c. Pupil round ; nostril in a single or seniidivided nasal; scales not oblique, 



short and smooth, in 15 or 17 rows. 

 Nostril directed upwards, nasal divided or semidivided; two 



superposed anterior temporals ; ventrals 145 or more Grayia. 



Nostril lateral, nasal entire ; a single anterior temporal; ventrals 



less than 145 Smnalosoma. 



