126 CATALOGUE OF MEXICAN ANIMALS. 



map containing portions of a particular State shall have been finished. 

 Every plan, map, or portion of a map prepared by the Geographical 

 Commission carries an inscrii)tion indicating the date of its preparation, 

 the persons by whom it has been prepared, and, in general, all the ex- 

 planations necessary to elucidate the history of its construction and the 

 degree of reliance which can be placed in it; the numerical data in- 

 cluded in the tables being referred to points plainly' visible and perfectly 

 fixed. This system, introduced by the Commission, has the advantage 

 of establishing several points of comparison wbich in future work may be 

 utilized for reference. The methods employed are the most exact ones 

 known which can be adapted to the circumstances of the country, sev- 

 eral new methods rendered necessary by special topographical conditions 

 having been devised by the Director. 



The work at the offices has been considerably facilitated by the estab- 

 lishment of small lithographic and photographic galleries at the head- 

 quarters of the Commission. At the former are printed the difierent 

 kinds of blanks and diagrams for the scientific service, including the 

 schemes for the geodetic and astronomical calculations, which when 

 brought t( gether form a collection illustrating the methods and instru- 

 ments rendered necessary by peculiar circumstances of travel and trans- 

 Ijortation. By means of these schemes there has been obtained a much 

 greater promptness in the work, more exact interpretation of the signs 

 in the employment of the formulas, and a uniformity which jjermits an 

 easy revision of the calculations should any be desired. In the photo- 

 graiihic gallery the reduction of the maps for different purposes is made. 



In the natural history division of the Commission the work has thus 

 far consisted in the preparation of a part of the geological map, corre- 

 sponding to two sheets of the general map, at a scale of 1:100,000, and 

 in bringing together an extensive collection of specimens of the different 

 branches of natural history, catalogues of which will appear in these 

 " Proceedings." 



The considerable expense necessary for the acquisition of the very costly 

 instruments to be used by the astronomical and topographical division of 

 the Commission has not yet permitted in the luitural history division the 

 formation of a library sufficiently complete to insure the success of its 

 work. For that reason no formal publication has been attempted as 

 yet; but when General Porfirio Diaz, who fully appreciates the impor- 

 tance of the work of the Commission, ordered it to take part in the 

 Exposition at New Orleans, the collections of natural history objects 

 were shipped in advance in order to have the identifications of the 

 specimens revised and completed before the opening of the Exposition. 

 Unfortunately, the steamer (the City of Merida) in which they were 

 shipped to New York was burned at Havana on the 29th of August, 

 1884:, causing the loss of the entire collection, consisting of 123 boxes, 

 besides all the baggage of the present writer, wherein was included all 

 the manuscripts pertaining to the collections. The Commission, desir- 



