460 
liarly compressed tail, the most striking character of the present 
genus. The general form of the head is similar to that of Cenchris, 
which it moreover resembles in having the anterior portion of the 
upper surface of the head covered with irregular shields of moderate 
size. Nostril in the middle of a single plate. Upper labials nine, 
the third, fourth, and fifth of which are the largest. There are about 
seven small shields between the orbit and the fourth and fifth. From 
the superciliary backwards the head is covered with keeled scales. 
Scales of the body keeled in very oblique series. 154 ventral shields ; 
anal entire ; 53 caudal shields. Posterior ventral shields extend very 
far up the sides. Colour green, paler and yellower below. A series 
of about thirty-five small golden-yellow spots runs along the back to 
the tail, where they become more irregular; each spot has a black 
edge posteriorly. The upper surface of the head is uniform dull 
green, bordered on each side by a black stripe proceeding from the 
eye to the side of the occiput. Length of the head | inch 4 lines ; 
of the trunk 2 feet 3 inches ; of the tail 6 inches. 
A single specimen only of this new species was preserved for me 
at Coban by Mr. Owen while I was away in the mountains of Lan- 
quin. It had been brought to him by an Indian. 
RANA HALECINA, Kalm. 
Common throughout Guatemala. It was the only species of Rana 
I met with. At Dueiias the Indians catch them to eat, spearing the 
larger ones and netting the larve. 
ENGYSTOMA CAROLINENSE, Holbr. 
Exceedingly common at Coban. In the day time they hide under 
stones and pieces of wood. About half the specimens I obtained 
have a fold in the skin across the occiput ; the rest are without it. 
This character therefore cannot be considered of specific value. 
Buro aqua, Latr. 
Very abundant at Lanquin and also at Coban, but the specimens 
from the latter place seem to be smaller. Though numbers were 
brought to me, there was not a single large one among them. ‘This 
species reaches its maximum development in the hottest parts of 
Brazil. It seems to diminish in size in more temperate regions. 
Buro NEBULIFER. 
Bufo granulosus, Baird & Girard, Proc. Ac. Phil. 1852, p. 173. 
Bufo nebulifer, Girard, Proc. Ac. Phil. 1854, p. 87. 
Very abundant at Dueiias, where they are to be found under stones 
and logs of wood. After dark they come out of their hiding places 
and may be seen hopping about im all directions. It is a species 
peculiar to Central America and Mexico. 
Hyxa HoLocuxora, sp.n. (Pl. XXXII. fig. 2.) 
Vomerine teeth in two slightly oblique series, beginning from the 
