246 THE EEPTILES OF EGYPT. 
labial glands), as they, in every case, gave rise to symptoms of poisoning exactly the 
same as those produced by the blood of the two snakes, •and were attended with 
the same result. MM. Phisalix and Bertrand's experiments show that the toxic 
principles of the blood of these snakes is derived from the internal secretion of the 
superior labial glands, and that the physiological and chemical similarity of the 
principles to echidnine explains the immunity of these snakes to the venom of the 
viper. Their experiments also establish that these serpents are in no sense harmless 
in so far as their prey is concerned. 
The discovery of venom secreting-glands in the Aglypha and in Opisthoglypha 
fully confirms Mr. Bouleuger's conclusion that the taxonomic division of Snakes into 
poisonous and non-poisonous, which he was the first to abandon, was erroneous '. The 
late Prof. Cope accepted this decided advance on the old classification. 
Tropidonotus tessellatus, Laur. (Plate XXXIV. fig. 1.) 
Tropidonotus tessellatus, Blgr. Cat. Snakes B. M. i. 1893 2 , p. 233, & iii. 1896, p. 605 ; Steindachner, 
Novara Exped., Reptiles, 1867, p. 66; Boettger, Zeitschr. ges. Natur. (Giebel), xlix. 1877, 
p. 287; Ber. Senck. nat. Ges. 1878-79, p. 64; S.B. Ak. Berl. 1888, p. 176; P. Muller, 
Verh. naturf. Ges. Basel, vi. 1878, p. 602; Carruccio, Bull. Soc. Zool. Rom. i. 1892, pp. 42 
& 45 ; Werner, Verh. zool.-bot. Ges. Wien, xlii. 1892, p. 355 ; Mehely, Zool. Anz. xvii. 
no. 442, 1894, p. 84; Peracca, Boll. Mus. Zool. Anat. Comp. Torino, ix. 1894, no. 167, 
p. 11 ; Ferreira, Jorn. Ac. Se. Lisboa, (2) iv. 1895, p. 42; Anderson, Herpet. Arabia & Egypt, 
1896, p. 106. 
1 2 . Beltim. Surgeon Lieutenant-Colonel J. G. Rogers, D.S.O., C.M.G. 
Rostral broader than high, visible on the upper surface of the head. Eye 
moderately large. Nasal generally partially divided, in contact with the first and 
1 Mr. Boulenger (Proc. Zool. Soe. 1896, p. 614) has shown that, so far as the jaws and teeth are concerned, 
a nearly complete filiation can be traced between the Colubridm Aglyphce and the Proteroglyphce on the one 
hand, and between the former and the Viperulai on the other hand. The following is the commentary 
of M. Phisalix confirming this opinion from a physiological standpoint : — " La decouverte des glandes 
venimeuses suivie de l'etude du venin et du sang, chez les couleuvres, a apporte a cette maniere de voir 
l'appui d'une verification experimental. Le venin et le sang de la couleuvre possedent en effet les memes 
proprie'tes physiologiques que le venin et le sang de la vipere, d'une part, et d'autre part, le venin et le sang 
des Proteroglyphes (cobra, ophiophage) determinent des symptomes d'empoisonnement completement 
differents de ceux de l'envenimation viperique. Si l'on ajoute a cela que le venin de couleuvre attenue par 
la chaleur ou inocule a dose non mortelle devient un vacein contre le venin de vipere et que les glandes 
labiales de la couleuvre, a l'egal de celles de la vipiire, vaccinent aussi coiitre son venin, on sera convaincu 
qu'il y a non seulement homologie, mais encore anahgie entre ces glandes, et que la parente entre les 
colubrides aglyphodontes et les viperides peut etre admise comme definitivement etablie." — 0. It. Soc. de 
Biol. ser. 10, iii. 1896, p. 965. 
2 As Mr. Boulenger has given the synonymy of this species, I have not done more than add a few 
additional references. A similar course has been followed with some of the remaining species. 
