10 BULLETIN 2 00, UNITED STATES NATIONAL MUSEUM 



There are four terms that are indispensable to a discussion of the 

 fundamentals of genotypy, in addition to the word genotype itself, 

 which is defined above. The general term for the legal establishment 

 of the correct genotype is fixation. This fixation of genotype may be 

 accomplished by various means, including designation, automatic fix- 

 ation, and fixation by special rules. Designation is fixation or selection 

 by direct statement, as "I designate the species 1 as type of the genus 

 A" or "Genus A, genotype = species 1." The genotype is automati- 

 cally fixed by monotypy when the genus originally includes a single 

 species. It is automatically fixed by objective synonymy when the 

 name is published as nomenclaturally equal to another name, as a new 

 name for it or as a stillborn synonym.^ (The term "objective" is 

 equivalent to "absolute" and implies that the synonymy is irrevocable 

 and not subject to opinion. The opposite is subjective synonymy, 

 which depends on the judgment of the taxonomist.) 



It is difficult to arrange the methods of fixation in order of impor- 

 tance. Yet this is essential since there are cases in which two different 

 species are indicated as genotype by two different methods. One must 

 obviously take precedence over the other. The following appears to 

 be the most satisfactory arrangement : 



METHODS OF FIXATION OF GENOTYPES 



A. Fixation under the Plenary Powers. 



1. Suspension of the Rules. 



B. Automatic fixation. 



2. Monotypy. 



a. Subspecies, varieties, synonyms. 



b. Included species not named. 



c. Since 1930. 



d. Virtual monotypy. 



e. Subgeneric monotypy. 



f. Synonymy of all original species. 



g. Original name must be available. 



3. Objective synonymy. 



a. Isogenotypy. 



b. Objectivity. 



4. Subsequent monotypy (of a genus without originally included species). 



C. Original designation. 



5. By direct statement of designation. 



6. Use of typicus or typus as a new specific name. 



7. Absolute tautonymy of a new specific name. 



8. N. g., n. sp. rule (Opinion 7). 



9. Single description rule (Opinion 43). 



*Thi8 term (stillborn) has been used In a somewhat confusing manner to signify a name 

 that was a synonym at the time of Its validation. It was first published as a synonym 

 and was in that sense "stillborn." However, such a name can be used under certain cir- 

 cumstances, so it is not actually "stillborn." 



