46 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
miles; then by train to Merida, Izamal, and Progreso. From Izamul a 
horseback trip was made some ten miles southeast to the cenote of 
Xcolak. 
Campeche and the Yucatecan Fauna. — The Gulf coast region 
presents quite the same coast view from the sea at Tampico, Yautla, Vera 
Cruz, Coatzocoalcos, Frontera, and Laguna — green the year round, and 
always tropical in aspect. But when we approach the coast in the vicinity 
of the city of Campeche, we behold a country of different aspect. Especially 
strong is the contrast in the dryest season of the year, in April and May. 
At this time, before the rains begin, the outskirts of Campeche and the 
coast in that vicinity (leaving out of consideration a few cocoanut 
palms) present the appearance of a desert mesa in winter in arid Texas 
and Yew Mexico. The scrubby growth of native bushes is sere and 
brown. Yo shades of green enliven the landscape or rest the eye. The 
crust of the earth is rocky and gravelly, while the heat is intense. These 
conditions obtain from Campeche eastward and northeastward over the 
whole northern half or more of Yucatan. It must be said that there are 
many stretches of wooded land in this extent of country, or patches here 
and there; but the trees have such a bizarre form, and wear such a woe- 
begone expression, in the dry season at least, that these stretches can 
not lay claim to the dignity of forest regions. The trees are of only 
moderate height, and the soil is so precarious and incapable of retaining 
moisture that they are rough, scrubby, and gnarled in growth, and most 
ungraceful in appearance. Yo handsome, symmetrical, and well-formed 
trees are to be seen in a state of nature. There is no green to be seen in 
the native vegetation except occasional clumps of a thorny bush which 
seems able to withstand the absence of moisture and still furnish green 
leaves. Square miles of henequen {Agave sisalana) grow everywhere, 
cultivated for the fibre. This plant may be taken as characteristic of this 
peculiar half-tropical and half-arid lowland district of Yucatan and 
Campeche. This country seems like an immense stretch of Lower Sonoran 
set down in the midst of the tropical, but scrupulously preserved intact, 
notwithstanding its direct contact with the latter over a wide area. Y othing 
but the peculiar geological conditions could so influence the meteorology, 
and through it the biogeography of a region; and here is furnished a hint 
which we may well heed in attempting to explain anomalies in geo- 
graphic distribution in other localities. Where the henequen will grow 
to good advantage may doubtless be taken to mark the extent of this 
flora and fauna, which must be considered as removed entirely from the 
Tamaulipan fauna, but analogous to the northern sub-arid portions of 
the latter. I have called this fauna the Campechian in my previous 
paper, but the term Yucatecan fauna is far more appropriate and cor- 
