LrNI^EA^ jOCiety of london. h 



arrangement, and execution of the scientific details (and as a model 

 I may refer to some of the publications of the Paris Museum, such 

 as the * Malpighiacege ' of Adrien de Jussieu), and also for the ex- 

 cellent woodcuts illustrating their general and popular works ; the 

 Germans and some Northern States for the admirable neatness of 

 microscopic and other minutiae executed at a comparatively small 

 cost, owing partially, at least, to the use of engraving on lithogra- 

 phic stone. 



4, Written descriptions are what we most chiefly rely upon to 

 convey to the general or to the practical naturalist the results of 

 our studies of animals and plants ; but descriptions are of two 

 kinds, individual descriptions and descriptions of species, genera, or 

 other races. The former are, like preserved specimens or delineations, 

 materials for study ; like them they require in their preparation little 

 more than artistical skill, guided by a general knowledge of the sub- 

 ject : but abstract descriptions, whether specific or relating to races 

 of a higher degree, require study of the mutual relations of in- 

 dividuals and races and their consequent classification which con- 

 stitute the science of systematic biology ; and this distinction should 

 be constantly kept in view for the just appreciation of all descrip- 

 tive works. Any tyro can with care write a long description of a 

 specimen unimpeachable as to accuracy ; but it requires a thorough 

 knowledge of the subject, and a keen appreciation of the bearing of 

 the points noticed, to prepare a good description of a species. Por the 

 latter to be serviceable it must be accurate ; it must be full without 

 redundancy ; it must be concise without sacrificing clearness ; it must 

 be abstractive, not individual ; and lastly, the most difficult qualifi- 

 cation of aU, and that which constitutes the main point of the 

 science, the abstraction must be judicious and true to Nature. 



The paramount importance of accuracy is too evident to need 

 dwelling upon. "We are all liable to errors of observation. Imper- 

 fect vision or instruments, optical deceptions, accidentally abnormal 

 conditions of the specimen examined, hasty appreciation of what we 

 see from preconceived theories are so many of the causes which 

 have occasionally led into error the most eminent of naturalists, and 

 require to be specially guarded against by repeated observation of 

 different specimens, and constant testiug at every step by reasonings 

 from analogy. Errors once established on apparently good authority 

 are exceedingly difficult to correct, and have been the source of 

 many a false theory. Where loose examination and hasty conclu- 

 sions have been frequently detected, we can at once renounce all con- 

 fidence in an author's descriptions, in his genera and species, un- 



^>^. 



Ojor 



