194 CH. WARDELL STILES, 



'"''Poris glöbosis, maximeque mohilibus, saepeque extantihus munitae'^ 

 confines the choice to those fish distomes betweea p. 352 and 415 which 

 show the characters referred to by repetition of these words or their 

 equivalents in the specific diagnosis. Any one of these forms 

 may be taken as type, provided that it has not already been taken as 

 type for another genus. D. itiacrostomum, which Looss suggests as a 

 possibility, was not available since this had already been eliminated 

 as type of ürogonimus. D. clavatum (as is now evident) was also not 

 available, since this is type of Hirudinella. 



In the description of D. globiporum (a distome of fish) we find 

 expressions which fully agree with Rudolphi's reference to Sphaero- 

 stoma globiporum: ''''Fori globosi apertura orhiculari, anticus exiguus^ 

 veniralis major, in junioribus prominulus, saepe sub animalculi motibus 

 maximam partem protrusus vel prolapsus.'''' Hence we are justified in 

 selecting this species as type. 



Further, earlier authors not infrequently selected a species which 

 they raised to generic rank, taking the name of that species as generic 

 name. In a number of cases in order to prevent tautonomy (as Trutta 

 irutta), the Latin or Greek specific name was translated into Greek or 

 Latin as a generic name, or another name of the same meaning was 

 selected, the old specific name was made generic while the new or the 

 specific name vulgaris was introduced. In such cases it is customary, 

 whenever this is possible, to select as type of the genus, that species 

 whose name agrees in form or meaning with the generic name {Älces 

 alces, Alle alle, ÄnJiinga anhinga, Bison bison, Bos iaurus, Buteo 

 huteo, Capra hircus, Cardinalis cardinalis, Coturnix coturnix, Crex 

 crex, JEquus caballus, Glis glis, Gulo gulo, Histrionicus histrionicus, 

 Lutra lutra, Meles meles, Ovis aries, Phocaena pJiocaena, Pipistrellus 

 pipistrellus, Porzana porzana, Puffinus puffinus, Rosmarus rosmarus, 

 RupicajJra rupicapra, Scomber scombrus, Sus scrofa or Sus porcus, 

 Sula sula, Tarandus tarandus, Trutta trutta, etc.) or one with which 

 the specific name vulgaris has been used. 



RuDOLPHi had a Latin specific name globiporum in the genus 

 Distoma; he suggested separating from Distoma a genus Sphaerosioma; 

 although he gave to the latter a poor diagnosis, Looss will surely 

 admit that this applies — so far as it goes — to globiporum. Instead 

 of taking a specific name {globiporum) and making it generic so as to 

 give tautonomous combination, like Trutta trutta^ he followed a not 

 uncommon custom in zoology, especially among early authors, in 



