194 Bihl{o(jraphical Xofice. 



42. 



Authors are urged to use only the metric system of -weights and 

 measures and the centigrade thermometer of Celsius. 



43. 



The indication of enlargement or of reductiou, which is necessary 

 to the comprehension of an illustration, shoidl be expressed iu 

 figures rather than by mentioning the system of lenses used. 



44. 



It is useful to indicate whether the enlargement is linear, or of 

 the surface, or of the mass. This may be easily expressed as 

 follows: — X 50' indicates a linear enlargement of 50 times, x 5U* 

 an enlargement of the surface, and x 50' an enlargement of the 

 mass. 



BIBLIOGRAPHICAL NOTICE. 



Rhopcdocera Exotica ; heing Illustrations of Ntiv, Rare, and Un- 

 Jjcjured Species of Butterflies. By H. (jrose-Smith and W. F. 

 KiRBY. Vol. II. London : Gurney and Jackson, 1892-97. 



The second volume of this well-known work should have received 

 notice at our hands before now ; but, as sometimes happens in the 

 case of a serial publication still in course of issue, the fact of the 

 volume's com])letion was overlooked. 



Unduly retarded, however, as our notice has been, the authors 

 may rest assured that there is no lack of appreciation on our part of 

 the manner in which the high standard ot their work has been 

 maintained. As they mention in their preface, nearly 250 species 

 are figured in this volume, the figures occupying sixty (]uarto plates, 

 and representing not only both upper and under sides, but iu a 

 large number of cases both sexes of each species. The colouring 

 throughout is excellent, but the drawing of a few of the smaller 

 figures is somewhat unequal in quality. It will be admitted, how- 

 ever, that the best executed figures in point of drawing are those 

 representing Oriental Lycaenidae (of the extremely beautiful genera 

 Thi/sonotis, Waigeum, &.C.), which for accuracy as well as for artistic 

 merit are admirable ; they are the work of Mr. Horace Knight. 



Butterflies of all families except the Hesperiidae find illustration 

 in this volume : but in the number of species described and figuied 

 the Lyctenidsp (10'-') far exceed the other groups. Xext come the 



