04 BUREAU OF ANIMAL INDUSTRY. 



intentions will usually be better carried out if a species of his personal 

 acquaintance is designated as type. If, however, it can be shown that 

 an author had some other species more particularly in mind, it is better 

 to select that form as type. 



17. PREFERENCE TO BE SHOWN TO SPECIES NAMED mmmuni#, vulgaris, officinalis, OR 



medicinalis. 



RULE. In case of Linnaean genera, select as type the most common, or a 

 medicinal species. 



RECOMMENDATION. Show preference to. a species bearing the name corn- 

 munis, Yulgaris, medicinalis, or officinalis, unless such preference is strongly 

 contraindicated by practical considerations. 



Linnaeus (1751, 197) laid down the following rule: '* Si genus recep- 

 tum, secundum jus naturae et artis, in plura dirimi debet, turn uomen 

 antea commune manebit vulgatissimse et officinali plantae." This, so 

 far as we know, is the earliest intimation of the general principle of 

 fixing a particular species as type of a genus. It certainly clearly 

 represents Linnaeus's intention regarding his own genera, and has the 

 great advantage of rendering more stable the generic names used by 

 nonzoologists. Just how far a rigid application of this rule, if applied 

 regardless of contraindications of a practical nature, would work to 

 the detriment of types accepted at present, it is difficult to state, but 

 in dealing with Linnaean genera his rule should be followed when 

 clearly applicable. 



In connection with genera of all authors it seems distinctly best to 

 show preference to species bearing the name communw, vulgaris, offi- 

 cinalis, or medicinalis, but it seems unwise to waive all other consid- 

 erations in favor of this process of selection. Among the nematodes 

 the species named communis are types for Filocapsularia, Desmodora, 

 Cylindrolaimus, Diphtherophora, and T&rschellingia, but not for 

 Spilophora (in which it was not an original species); vulgaris, for 

 Comesoma, Chromadora, Euchromadora, GrapJwnema, Loinbricoides, 

 and Tripyloides. 



Ts&nia Linnaeus, 1758a, may be mentioned as a case where practical 

 considerations at present distinctly contraindicate the selection of vul- 

 garis as type of a Linnaean genus, but the selection of solium as type 

 of Tsenia does not seem to be contrary to the Linnaean rule. 



18. THE BEST DESCRIBED, BEST FIGURED, BEST KNOWN, OR MOST EASILY 

 OBTAINABLE SPECIES. 



RECOMMENDATION. Other things being equal, select as type that species 

 which is best described, or best figured, and for which both sexes are 

 described, or a species which is best known, or most easily obtainable, or 

 most common, or of which a type specimen can be obtained. 



That the best-described species should frequently be given prefer- 

 ence is a natural proposition, but an author should be governed by 

 various considerations in this matter. It is. for instance, sometimes 



