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Book Notice. 



A Preliminary Monograph of the North American species of Trogophloeus ; 

 by Capt. Thos. L. Casey. Ann. N. Y. Ac. Sci., v. IV, 1889, pp. 322—383. 



In this paper, Capt. Casey seems to have done good work so far as 

 it is possible to judge without actually testing it in collections. The 

 characters used seem clear, the tables are concise, and the descriptions 

 terse — an inprovement perhaps on former papers where excessive length 

 of description was criticised. No se.xual characters are used or even 

 mentioned, though in many other Staphylinide genera they are of the 

 highest value. 66 species are recognized, most of them new, and a 

 large proportion of them based on single specimens — a peihaps unavoid- 

 able element of weakness, since it is much more difficult to judge of the 

 value of characters. In some respects the most interesting part of the 

 paper, and one meriting thought, is in the introduction, largely devoted 

 to defending the microscope versus the hand lens, and somewhat im- 

 pugning the value of results attained by using the latter. Now here an 

 element comes in which Capt. Casey himsell recognizes, when he speaks 

 of "the novice who has not yet learned to inter[)ret what he sees" — it is 

 the experience of the user of either lens or micfoscope. Behind each is 

 an instrument which is much more important —the trained e\e of the 

 observer — the eye that with a good triplet can count the joints of a 

 Trichopterygid antenna, while the untrained u^er of the compound mi- 

 croscope cannot with an infinitely greater magnifying power be sure any 

 joints exist. Now I am a believer in the microsceipe, and I u^e it con- 

 tinually in my work. I have had a binocular stand in use for several 

 years, and have a very fine instrument for my college work — yet it has 

 happened to me frequently that I have taken a specimen from the micro- 

 scope and studied it with the lens with much more satisfactory results. 

 I saw more and saw it better. Increase in the size of the image does 

 not always import increased distinctness of detail. D.scretion in the use 

 of appliances must be exercised and the man wlio uses a microscope 

 only, is apt to make as many errors as a man using the lens only. It is 

 in the interpretation of what is seen, that the errors are made. It is the 

 experience of the observer, and his ability to select those characters 

 which are of importance, that determines the character of the work : that 

 experience which enables a man to recognize specific characters among 

 the assemblage presented by any given group of insects — which enables 

 him to recognize the limits of variation — which will enable him to dis- 

 card striking modifications in many instances as unsafe, and rely upon 

 inconspicuous features for specific characters. No hard and fast rules 

 can be formulated for the conscientious student : he will be a "lumper" 



