224 DR. H, GADOW ON MEXICAN [June 6, 
southern half; coloured and behaving exactly like Hlaps, it is 
often mistaken for a true “ Coralillo,” 
Urotheca, Dromicus, Drymobius, and Leptophis are mainly 
Central and South American with species in the Antilles, extend- 
ing northwards into the Atlantic and Pacific Tierra Caliente, on 
the east side even into Texas. Drymobius margaritiferus is the 
commonest tree-snake. D, boddaerti ranges from South America, 
Trinidad and 8. Vincent, and on the Pacific side it has been 
brought from Tres Marias Islands. 
Rhadinea is South and Central American, going into Mexico 
east and west and onto the slopes of the Southern plateau. 
Urotheca likewise Central and South American and Cuban ; 
U. elapoides from Costa Rica along the Atlantic side to Orizaba, 
Streptophorus typically Central American, extending into the 
Atlantic Tierra Caliente. S. diadematus from Tabasco through 
Oaxaca to Jalapa and Orizaba. SS. atratus from Ecuador and 
Venezuela to Jalapa, None is Antillean. 
Hypsiglena torquata from Venezuela to California, in Mexico on 
the plateau and the Pacific side. 
Atractes, Tropidodipsas, Dirosema, and Geophis are Southern 
genera, extending into the Atlantic and Pacific Tierra Caliente, 
the last genus with more western range. GG. (Geagras) ridimita 
I have found in the sand-dunes of the lagoons near Tehuantepec. 
OpistHogLyPHA.—7rimorphodon, a Mexican genus with western 
preference. 7’. wpsilon extending northwards into Arizona, south- 
wards to Panama; 7’. biscutatus distinctly Pacific from Mazatlan 
to Panama; 7’. aw on the Isthmus of Tehuantepec, 
Himantodes, a typical Neotropical forest genus, of which H. 
cenchoa has spread into the Atlantic, H. gemmistrata and 
H. tenuissima into the Pacific Tierra Caliente. Cope’s statement 
that H. gemmistrata has been found at Toluca seems to be 
erroneous. 
These 'Tree-snakes are called “‘Stchil” in Oaxaca and on the 
Isthmus, are feared as poisonous, and are said to attain a very 
ereat length. Every snake, when in motion, appears to be much 
longer than it is, and these active creatures gliding rapidly through 
the dense canopy of a tropical forest seem indeed to give one the 
impression of prodigious length. Another name for Tree-snakes 
is ‘¢ Bejuquillo,” in allusion to lianas, which are called bejuco. 
Leptodira, Neotropical, into the eastern and western Tierra 
Caliente, remaining outside the plateau, although ZL. albofusca, 
which extends to Para and Ecuador, ascends outlying mountains, 
like the Nevado de Colima, up to 7000 feet. Z. septentrionalis, as 
the most northern offshoot, occurs in Texas and New Mexico. 
Oxyrhopus, essentially South and Central American; 0. cloelia 
and O. plumbeus stop at the Isthmus of Tehuantepec ; O. petiolarius 
goes into Guerrero. This genus is of special interest since it 
contains the only Opisthoglyph which has reached the Antilles, 
but only the Lesser. 
