DETERMINATION OF GENERIC TYPES, ETC. 31 



sight we may ascribe much of the confusion in nomenclature which 

 has arisen. Helnrinthologists in general laid little stress upon type 

 species prior to the publication (1898) of the '"Inventory of the 

 genera of the trematode family Fasciolidre.'' Blanchard in particular 

 should be mentioned as preeminent among helminthologists to insist 

 upon the importance of type species (see particularly his writings on 

 nomenclature), while even such eminent men as Rudolphi, Dujardin, 

 Diesing, Molin, Leuckart, and others paid little or no attention to 

 this important part of the generic diagnosis. 



ROUNDWOEM GENERA WITH TYPES BY ORIGINAL DESIGNATION. 



Exclusive of those cases where an author has intentionally renamed 

 a monotypical genus (to which other species may later have been 

 added), and exclusive of the cases where the specific name typicus or 

 typus has been used, there are only about ten instances in roundworm 

 genera in which the author of a genus (originally containing several 

 species) has definitely determined a type by original designation, 

 namely : 



AnoplostomaBueischYi, 1874b (viviparum) . 

 Bunostomum Railliet, 1902 (trigonocepha- 



lum). 



Desmodora de Man, 1889 (communis). 

 Euchromadora de Man, 1886 (vulgaris). 

 Gongylonema Molin, 1857 (minimum). 



Heterakis Dujardin, 1845a (vesicularis) . 

 Leptosomatum Bastian, 1865 (elongatum). 

 Monoposthia de Man, 1889 (costoto). 

 Neoechinorhynchus Hamann, 1905 (davse- 



ceps). 

 Stenolaimus Marion, 1870 (lepturus). 



In connection with the genera whose types were determined by orig- 

 inal designation, it may be well to note the following hypothetical 

 case as example of instances which are not uncommon: 



X-us, 1890, with the species albus, 1890, type by original designation. 



Let us assume that Dr. A, in 1895, suppresses X-us as a synonym 

 of Y-us, 1885, type niger. If later Dr. B, in 1900, separates X. albus 

 generically from Y. niger, reinstituting the genus X-m, albus must of 

 course remain the type of X-us. This ruling is in accord with various 

 codes, and appears to have been first formulated in the B. A. Code 

 (see above, p. 14). 



Other cases, slightly more complicated, will be referred to under 

 another section. 



4. TYPE BY ORIGINAL IMPLICATION THROUGH USE OF THE SPECIFIC NAME typicus 



OR typus. 



RULE. If in the original publication of a genus, typicus or typus is used 

 as a new specific name for one of the species, such use shall be construed as 

 " type by original designation." 



The canon here formulated agrees, so far as we have been able to 

 discover, with the customs adopted by systematists both in zoology 

 and botany. Its adoption will probably meet with general approval. 



