378 Bibliographical Notices. 



Hob. Ecuador? 



Of the two skins in the Museum one was in Gould's 

 Collection and one in our own, the latter having been obtained 

 from Mr. Whitely. Both are males. The exact locality 

 where this bird is found remains to be discovered ; at present 

 I can only say that the types are made up in the manner 

 usual in collections of humming-birds from Ecuador. 



Eriocnemis ventralis. 



Adult male. Upper surface shining grass-green, becoming 

 bronzy black on the hind neck and crown, and glittering 

 olive-green on the rump and upper tail-coverts ; under sur- 

 face with the throat bronzy black, a glittering blue gular 

 patch ; breast glittering green, shading into glittering 

 amethyst on the abdomen ; under tail-coverts glittering 

 purplish blue ; tail steel-blue ; tibial tufts pure white ; bill 

 black. Total length about 3*9 inches, wing 2*25; tail, 

 central rectrices 1*05, lateral L65; bill 0"85. 



Hab. Colombia. 



BIBLIOGRAPHICAL NOTICES. 



Aids in Practical Geology. By Grentille A. Cole, F.G.S., Professor 

 of Geology in the Royal College of Science for Ireland. 8vo. 

 Pp. i-xiv & 1-402 ; with 136 illustrative cuts. C. Griffin & Co. : 

 London, 1891. 



Chapter I. treats of Geological observations to be made in the 

 field, from lowland to upland and into the mountains, with the 

 utensils required and the methods recommended. For the construction 

 of maps and sections, Geikie's and Penning's books are referred to. 

 Mr. Dalton's geometric process of determining the true dip between 

 two uncertain dips in the sides of a quarry is given at page 6. For 

 labels, mentioned at page 10, good pencil-writing will surely resist 

 moisture better than ink. Chapter II. is short, but important ; 

 treating of the collecting and packing of specimens. 



As the chief aim of this excellent manual is to teach the student, 

 whether indoors or abroad, to recognize the various kinds of Rocks — 

 sedimentary, igneous, and mctamorphic — that constitute tho solid 

 portions of the Earth's surface, the knowledge of how to find out 

 and discriminate their constituent minerals is of primary importance. 

 Hence Chapters III. -IX. (pp. 13-83) treat of the physical characters 



