186 
THE POISONOUS SNAKES OF THE ANGIjO-EGYPTIAN SUDAN 
to its refuge at the approach of man (though fiercely defending itself by biting when caught), 
I do not believe that it is to be feared in any way. A figure of its head is given on 
Plate XX., fig. 3, c. Coloration, brown above, with a more or less distinctly yellow line in 
the middle of the back ; lower surface, white anteriorly to yellow in the posterior part. 
The ScaliiKj (if (i SiKike’K Jleiid (Did Ihjdij 
The upper liji of all Sudanese snakes is bordered by a row' of more or less enlarged 
plates, the upper labials (u.l.); the middle one on the end of the snout, and emarginated 
below', to allow the tongue to be protruded from the mouth, is called the rostral (r.). .\t 
each side of tlie head we find a nasal (n.) sliield, perforated liy the nostril and often divided 
vertically (the hind part, in addition, horizontally in radiniiKiphis sihiUiiis). This shield is 
follow'ed liaekw'ards by a loreal (1.), elongate in Fsainiiid'phis, missing in Naja and Atractas'pia, 
indistinguishalile in the snakes w'ith many small head-scales, like Bitia, Cerastes and Echis. 
Behind tlie loreal, and between this and the eye, w'e find the prie-ocular (one or two, rarely 
more); behind the eye, the post-oculars (tw'o or three, rarely one). The eye may be separated 
from the uiiper labials by suboculars (see Naja hajie, Causvs), even occurring in several 
rows, as in Bitis, Cerastes, Echis, or some of the uiiper labials may enter the eye 
{rsainindphis, Atraefaspis, Naja itiijricullis). Tlie temples behind the post-oculars are covered 
with temporal scales (t t') in several rather vertical rows, only the first two rows being, 
however, counted in the descriptions. 
The upper surface of the head beliind the rostral is covered by nine large plates (four 
pairs and one unpaired), in I’samtiinphis, Naja, Caiisus and Atnictaspis, by small keeled ones 
in Bitis, Cerastes and Echis. The plates are called as follows, from snout to back of head : 
inter-nasals (between nasals) (i.), pra;-frontals (pf.), supra-oculars (so.); betw'een these the 
median frontal (fr.), behind them the parietals (p.). Lower surface of head: round the 
lower lip = lower labials ; the middle one below the rostral = symphysial; behind the 
symphysial = the chin-shields, one or two x'airs ; behind them the gular scales, followed by 
the broad ventrals (fig. 2), which cover the whole lower surface of the body ; the last ventral 
covering the vent, longitudinally divided or entire, is the anal. The tail is covered 
below by the subcaudals (single like the ventrals in Atractaspis and Echis, paired in the 
others). The scales of the upper parts of body and tail are arranged mostly in longitudinal 
rows. They are counted on the thickest part of the body obliquely across the back from 
one side of the enlarged ventrals to the other; they are nearly always in odd numbers 
in the Sudanese species. 
