1899] COLOMBIAN ORE 295 



the specimens begins. Preceding such descriptions there is in each case a 

 preliminary historical account of the mining done in the district from which the 

 specimens were collected. The sulphide ores are chiefly those of silver, zinc, 

 mercury, lead, and iron, and occasionally of antimony, etc., while large amounts 

 of native gold, silver, and sometimes copper are present in many of the districts. 

 Among the sulphides pyrites is very common, and this is sometimes auriferous. 

 Occasionally copper pyrites, mispickel, stibnite, cinnabar, tetrahedrite, pyr- 

 rhotite, enargite, etc., are present. The gold is frequently associated with 

 tellurides. Many interesting examples of paragenesis are given, but to enter 

 into details would be wearisome to the general reader, although they might be 

 perused with avidity by those interested in the mines of this republic, while 

 the mineralogist could not fail to find some useful information in them. One 

 of the most important points with which the author has dealt is the true 

 signification of the names of rocks hitherto employed by former writers when 

 describing these mines. For instance, for the old terms syenite and granite, the 

 author points out that one may generally read andesite or trachyte ; " horn- 

 blendic material " usually is found to be a rock allied to chlorite schist, and 

 several other examples of the former misapplication of names, owing to lack of 

 the present means for determining the mineral constitution of rocks, will be 

 found in these pages. The author has done useful work in solving some of 

 these enigmas. 



In the "General Conclusions," p. 172, he remarks that "the gold and silver 

 ores of Colombia occur either in the acid lavas, which have been erupted at 

 intervals from the close of the Tertiary to the present time, or in Archaean 

 schists in the immediate vicinity of the lavas. In the schists they are usually 

 poor in depth. Owing to the action of the heavy tropical rains, the weathered 

 zone of the deposits has often been greatly enriched, and it was such enriched 

 deposits that gave the immense yields of the early days of Colombian mining." 



Three pages, giving the literature relating to Colombian mines, are followed 

 by a map, on which considerable labour has evidently been expended in order 

 to render the topographical details trustworthy. F. Rutley. 



COCCIDOLOGY. 



The Coccidae of Ceylon. By E. Ernest Green. Part I. 1896; pp. 

 i.-xi. + 103, with pis. 1-30. Part II. 1899 ; pp. xiii.-xli., 105-169, and 

 pis. 31-60. London: Dulau and Co. 



The Coccidae constitute an aberrant group of the Hemiptera, contradicting 

 all ordinary definitions of the order and class to which they belong. Hemi- 

 pterous hexapods, yet in the female sex wingless, and in many genera legless 

 as well. The very methods by which they must be studied are peculiar, and 

 as such distasteful to the ordinary entomologist. 



So it has happened that these creatures, though numerous and peculiar, 

 have been greatly neglected. But in recent years, as though outraged by such 

 persistent scorn, they have risen in their might and played havoc with our 

 fruit trees and other crops, not to mention ornamental plants ; wherefore we 

 have been obliged to recognise their existence. 



Studies usually begun with economic ends in view have led us far afield. 

 It becomes plainer every day that the Coccidae are not only extremely numerous 

 in species, but offer an extraordinary series of peculiar forms, Avhose organisation, 

 as related to their environment and habits, is of the greatest interest from a purely 

 biological standpoint. The opportunity to advance both economic entomology 

 and pure science is too good to be neglected once perceived ; and so we find a 

 new body of students arising, calling themselves coccidologists, and dignifying 

 their study by the name of coccidology. 



Of these latter-day students assuredly E. Ernest Green is second to none. 



