6894 Arachnida, 



Not rare denotes that a close search will generally procure what 

 we call " a few," that is, from five to ten or a dozen. 



Occasional denotes that during the time stated, and with careful 

 search for it, two or three may be captured. 



Ra7'e would show that a specimen only would be likely to be 

 obtained, as we should say " once now and then," that is, about once 

 out of several afternoons' very careful search. 



Ver^ rare would denote that one or two specimens in the run of 

 a season, would be all that a careful search and open-eye for it would 

 obtain. 



It will perhaps appear trivial to some to attempt to define these 

 general expressions. It is, I admit, very diflficult to do so, for we 

 know that their force will vary according to the number of hours, or 

 the state of weather, during which the search is carried on ; and 

 again, according to different persons' powers of close search, that is, 

 their power of concentrating the attention on one object, for this is 

 really, 1 believe, the secret of obtaining so-called rarities. And 

 again, the knowledge or ignorance of the habits of the species 

 searched for, and in fact many other things, will come in to prevent 

 perfect uniformity of meaning, whatever terms we may choose for the 

 purpose of specifying relative abundance ; yet the want of a little 

 more accuracy and uniformity than now exists will always, it seems 

 to me, take away more than half the real value of local lists of 

 species. And in regard to other parts of Natural Science, the want of 

 uniformity of use and meaning, has produced and still produces great 

 confusion and hindrance; I allude to the sense attached by difierent 

 naturalists to the words " order," " family," " tribe," " genus," 

 " subgenus," &c. And how few systematic works on Natural History 

 state the principles of their systems, the meanings of their classi- 

 fication, the values of their divisions ; what one may call a " tribe " 

 another calls a " family," and so on. And even the careful reader is 

 often compelled to stop in the study of his favourite branch of Natural 

 History, perplexed by a perfect labyrinth of classification, and with- 

 out any clew as to whether his author looked on the names of 

 the divisions of his system merely as bare landmarks to direct the 

 traveller into unknown regions, or as terms to point out real divisions 

 written and existing in Nature herself, and so only to be set up where 

 the divisions exist in Nature, without regard to the mere convenience 

 of students and collectors. So that I repeat the want of attention to 

 an uniformity of use and meaning of words does seriously retard the 



