INTERNATIONAL RULES FOR ZOOLOGICAL NOMENCLATURE. 209 



Recommendations. — It is well to avoid the introduction of new generic 

 names which differ from generic names already in use only in termination or in a 

 slight variation in spelling which might lead to confusion. But when once intro- 

 duced such names are not to be rejected on this account. Examples : Picus, Pica ; 

 Polyodus, Polyodon, Polyodonta, Polyodontas, Polyodontus ; Macrodon, Microdon. 



The same recommendation applies to new specific names in any given genus. 

 Examples : necator, necatrix ; fercigera, fercifera ; yhopalocephala, rhopaliocephala. 



If from the radical of a geographic name, two or more adjectives are derived, 

 it is not advisable to use more than one of them as specific names in the same 

 genus, but if once introduced, they are not be rejected on this account. Examples : 

 hispaniis, hipanicus ; vtolnccensis, f/ioluccanns ; sinensis, sinicus, chinensis ; 

 cylonicus, zeylanictts. 



The same recommendation applies also to other words derived from the same 

 radical and differing from each other only in termination or by a simple change in 

 spelling. Examples : caricletis, ccerideiis ; silvesti-is, sylvestris, silvaticus, sylvati- 

 cus ; lifforalis, litoralis ; autwnnalis , anctiimnalis ; datim, daniina ; fluvialis, 

 fluviatilis, fluviaticns. 



AP PEND IX. 



A. — It is very desirable that the proposition of every new 

 systematic group should be accompanied by a diagnosis, both indi- 

 vidual and differential, of said group in English, French, German, 

 Italian, or Latin. This diagnosis should state in what museum the 

 type specimen has been deposited, and should give the museum 

 number of said specimen. 



B. — In publications issued in any other language than English, 

 French, German, Italian, or Latin, it is very desirable that the 

 explanation of figures be translated into one of these tongues. 



C — The metric system of weights and measures and the centi- 

 grade thermometer of Celsius are adopted as standard. The micron 

 (0,001'""') represented by the Greek letter /x, is adopted as the unit 

 of measure in microscopic work. 



D. — The indication of enlargement or of reduction, which is very 

 desirable for the comprehension of an illustration, should be expressed 

 in figures rather than by mentioning the system of lenses used. 



E. — The indication of enlargement or reduction of an object is 

 usually linear. The sign of multiplication is used for enlargement, 

 and the fraction for reduction. Examples : x 50 indicates that the 



object is enlarged 50 times; — indicates that it is reduced to — th. 



If it is desired to specify that the enlargement is linear, surface, 

 or mass, this may be done as follows : x 50^ indicates linear enlarge- 

 ment ; X 50- indicates surface enlargement ; x 50^ indicates mass 

 enlargement. 



