PHYLOGENY OF VENOMOUS SNAKES 49 
ciple as echidnin. Jourdain (1894) found that Tropidonotus viperinus, 
Elaphis esculapti, Coronella levis and Rinachis scalaris enjoy the same 
immunity against the viper’s venom as T'ropidonotus torquatus. He held it 
certain that these snakes have the venom-producing apparatus and contain 
its product in the blood. Jourdain ventured a still more far-reaching gen- 
eralization, that every snake is provided with the venogenous gland. 
While the experimental data concerning the toxic property of the posterior 
yellowish portion, alleged to be homologous with the real poison gland by 
Leydig, are strikingly meager, a mere anatomical investigation into the extent 
in which that particular portion of the supralabial gland comes into existence 
among the non-poisonous species seems. to warrant enough interest to be 
briefly dwelt upon in this place. Several species of the Aglyphous snakes 
have been studied by some investigators. Of the subfamily of Natricinz (or 
Colubrinz) some species of the genus Naérix (or Tropidonotus), of the sub- 
family Coronelline, some species of the genus Elaphe (s. Coluber), Ptyas (s. 
Coryphodon) and Herpetodryas,* and of the subfamily Rhachiodontine, the 
genus Daspeltis have been studied. 
Tropidonotus natrix s. Natrix torquatus Fleming: the glandula labialis 
superior consists of a grayish and a yellowish portion. The glandular grains 
are made of aggregates of tubules. The cellular elements of the yellowish 
portion are filled up with granules, and appear like the rennet cells. The 
epithelium of the excretory duct is a high, clear cylinder cell. The entire 
yellowish part is provided with one single duct, while the anterior parts 
have many small ducts opening near the teeth. Leydig (1873) drew an 
analogy between the yellow portion and the parotid of the mammalia. The 
posterior part of the yellowish portion is described by Leydig as having 
the dark, granulated epithelium. Reichel described a similar character of 
the cell and added that the nucleus is situated basally. The examination 
of the grayish part reveals many tubules with clear cylindrical cells, which 
show transverse striation when treated with osmic acid. The reddish- 
grayish portion contains transparent, non-granulated cells, which are cylin- 
drical and have basal nuclei. Sometimes there are smaller, highly granulated 
cells with nuclei dislodged. These are usually met with in the edge of the 
acini. Some alveoli may consist entirely of this type, others chiefly of the 
first-named kind, and still others of a mixture of the two types. Reichel con- 
sidered these varying types of the epithelia as the representatives of different 
stages of cellular activity, the first type being the resting state. 
Tropidonotus subminiatus Reinwardt: Niemann (1892) has described the 
supralabial and the yellowish gland separately. He found four smaller 
excretory ducts in the former and one larger for the latter. The yellowish 
gland is surrounded by a strongly developed connective tissue capsule, which 
has a circular cleft to allow the entrance of the blood-vessels. The long-oval 
tubules of the gland are surrounded by a thin, delicate connective tissue mem- 
brane. “The glandula labialis superior is wrapped up in a layer of strongly 
developed connective tissue, within which a lymphatic space is also present. 
Pee a ee eee Ba a ee 
1Probably synonymous with Liopeltis Fitzinger. 
