650 MR. G. A. BOULENGER ON THE 



17. HOMALOSOMA. 



Wagl. Syst. Araph. p. 190 ; Bouleng. Cat. Sn. ii. p. 273. 



1. HoMALOSOMA LUTRIX. 



Coluber lutrix Linn. S. N, i, p. 375. 

 Homalosoma lutrix Bouleng. t. c. p. 274. 



Homcdosoma shiranum et abyssinicum Bouleng. t. c. p. 276, 

 pi. xiii. figs. 1 & 2. 



East, Central, and South Africa, as far north as Abyssinia. 



18. Dasypeltis. 

 Wagl. Syst. Amph. p. 178 ; Bouleng. Cat. Sn. ii. p. 353. 



1, Dasypeltis scabra. 



Coluber scaber Linn. Mus. Ad. Frid. p. 36, pi. x. fig. 1. 



Dasypeltis scabra Bouleng. t. c. p. 354. 



Tropical and South Africa, Egypt ; South Arabia. 



B. Opisthoglyplia. 



I. Eye rather small, inoderate, or large, with vertically elliptic or snhelliptic pupil ; 



ioreal present; nasal, if not completely divided into two, with horizontal cleft. 



A. Nostril hetween two nasals. 



Scales in 21 or 23 rows ; ventrals 142-153 ; suhcaudals single, 



35-44 Diti/pnpJiis. 



Scales in 19 to 23 rows; ventrals 205-274; suhcaudals 61-86 



pairs TarhophU. 



Scales in 19 rows ; ventrals 144-180; suhcaudals 32-54 pairs,.. Leptodira. 



B. Nasal semidivided ; scales in 17 (rarely 19) rows ; ventrals 



148-173; 187: suhcaudals 61-78 Hemirhagerrliis. 



II. Ej^e moderate or large, with round or horizontal pupil; Ioreal present. 



A. Pupil round. 



1. Loreal not more than once and a half as long as deep ; scales not ohlique. 



a. Nostril round ; scales in 17 rows. 



Nostril in a semidivided nasal ; rostral hroader than deep, just 



visihle from ahove Amplorhinus. 



Nostril hetween two nasals and the internasal ; rostral as deep 

 as hroad, its upper portion at least half as long as its 

 distance from the frontal Trimerorhinus. 



b. Nostril a crescentic slit in a divided or semidivided nasal; scales in 17 



or 19 rows. 



Suhcaudals less than 80 Coelopeltis. 



Suhcaudals 90 or more Bhamphiophis. 



2. Loreal at least once and a half as long as deep ; scales more or less oblique; 



suhcaudals 78 or more. 



Scales in 17 rows; a single anterior temporal DromopMs. 



Scales in 13 to 19 rows ; usually two superposed anterior tem- 

 porals; one or two anterior maxillary teeth much enlarged, 

 fang-like Psammophis. 



3. Loreal not more than once and a half as long as deep : 



nostril in an undivided nasal ; scales very narrow, 



very oblique, keeled, in 19 or 21 rows JDispliolldus. 



B. Pupil horizontal ; nostril in an undivided nasal ; scales 



narrow, oblique, feebly keeled, in 19 rows Tlielotornis. 



