58 MEXICO, CENTEAL AMERICA, WEST INDIES. 



Scorpions are one of the plagues on the plateaux, where the fields are also 

 ravaged by Tarions species of acrita. The nights in the tropical zone are lit up at 

 night by the firefly [cocuyos), flitting and flashing in the air like coruscations. 

 The ant is represented by numerous species, one of the commonest of which are the 

 arriéras, or "muleteers" (cecodoma mexicana), who excavate their crater-like habi- 

 tations in the hardest rock. 



One of the most interesting of the lower organisms observed by naturalists on 

 the Anahuac plateau is the curious axolotl, which has been the subject of pro- 

 found studies in connection with the theory of evolution. It abounds especially 

 in the saline and sodic waters of Lake Texcoco, and has rarely been met in other 

 parts of the New "World. It is a species of amphibious lizard, furnished with 

 bronchial tufts or gills, but liable to such Protean changes that its classification 

 presented great difiiculties to the first observers of this eccentric creature. They 

 gave it all sorts of scientific names, even that of lusus aquarum, " sport of the 

 waters," and it was then constituted a separate genus under the title of siredon. 



Nevertheless, many zoologists already pronounced it to be the larval form of a 

 large species of amhlyatome, and this view was at last proved to be correct by 

 Dumeril, who gradually transformed the axolotl to an amblystome. Most of the 

 axolotls remain for several generations in the larval or tadpole state, and a few 

 only develop into the perfect animal. The Indians consider its flesh a great 

 luxury, and they also greedily devour the eggs deposited by two species of the 

 arayacatl fly (especially the corixa femornta) amongst the sedge of the Mexican 

 lakes. These eggs are pounded and mixed with other ingredients to form cakes, and 

 nests of other larvae, clustered together like sponges, are also eaten. According to 

 Yirlet d'Aoust the eggs of the axayacatl deposited on the bed of lakes, hardens to 

 a kind of oolitic limestone exactly similar to that of the oolites of the Jura, which 

 Were probably formed in the same way. 



The marine waters on both sides of Mexico abound in animal life. Amongst 

 the cetaceans that visit its shores are some manatees. Hundreds of new species of 

 molluscs have been discovered on the Pacific side, amongst others the aptma 

 depilans, which would appear to be the same as that from which the Tyrians 

 extracted their purple dye. The Indians of Tehuan tepee use it for dyeing their 

 fibres, without requiring a mordant to fix the colour. 



In the Gulf of California, and especially near Paz and the neighbouring archi- 

 pelagoes, extensive beds of pearl oysters are fished. Some other islands in the same 

 gulf are frequented by myriads of various species of aquatic birds, and have already 

 yielded many hundred cargoes of guano. 



It is noteworthy that the Pacific islands lying at some distance from ihe coast 

 have all a fauna different from that of the mainland. Thus the little Tres-Marias 

 group, about 60 miles off the coast of Jalisco, has a special species of humming- 

 bird. The Pevilla-Gigedo archipelago also forms a separate zoological zone, and 

 the island of Guadalupe, 155 miles distant from Lower California, has eleven 

 species of land birds, every one of which differs from the corresponding species on 

 the adjacent continent. 



