206 PKOCIOKDINGS OF THK M A LACOLOOICA I, SOCIKTY. 



IV. The name of a superfamily is formed by addinj^ the ending 

 oidece^ to the stem of the name of its type genus. Family, sub- 

 family, and superfamily names are subject to the law of priority, and'; 

 from a nomenclatural standpoint may be regarded as co-ordinate andi 

 interchangeable. 



XXI. In the instance of a name published by one writer and 1 

 attributed to another, and it is not clear from the context which i 

 author is responsible for the accompanying description, definition, or i; 

 indication, the publishing author shall be held responsible for the x 

 name in all instances except («) where it had been previously used as si 

 a nomen nudum by the autlior to whom it is attributed, or {b) it is 5 

 subsequently claimed by the latter author in another publication. 



XXV [b). Generic names, whether accompanied by a definition or 

 not, under which no species or merely manuscript species are cited 

 or indicated (excluding as a matter of course instances where the 

 diagnosis of a species and genus are gi%'en as one), are not formed in 

 accordance with the fundamentals of binomial nomenclature, and 

 have no status under the Code. iSuch names take status only 

 when reintroduced in the proper manner and from the time of 

 reintroduction.^ 



XXX (iii). If a genus without a definitely designated type 

 contains as an available species one which has been repeatedly 

 mentioned as an illustration, example, or characteristic representative 

 of the genus, said species shall be virtually regarded as type by 

 subsequent designation. 



Principal Literatuke. 



Except in a few instances figures, references, or discussions of the 

 species recognized in the preceding pages may be found in the 

 following papers. It is the intention of the writer to supplement 

 this article with detailed studies of each group, amply illustrated, as 

 rapidly as possible. 



General Papers. 



Dall, W. H. Land and Freshwater Mollusks of Alaska and adjoining 

 Regions (Harriman Alaska Expedition, xiii, 1905, pp. 171, 3 plates, and 

 many text-cuts). 



An indispensable handbook covering the district north of the 49th 

 parallel. The treatment of the LymnseidEe and other groups whose 

 metropolis is essentially boreal is far superior to that of any other writer. 



Hannibal, H. " Shells of Lakes and Streams," in Keep, West Coast Shells 

 (revised edition), December, 1910, pp. 299-318, 3 plates, and several 

 text-cuts. 



^ T. Gill, Smith. Eeport for 1896, 1898, p. 480. The termination oidea, first 

 suggested in this connexion, is preoccupied by its use as a generic ending, 

 cf. Cyrenoidea. Acea has appeared in one or two papers, but was originally 

 applied by the Adams as an ordinal termination, and must be suppressed 

 for a group of different rank. There is no apparent reason why it should 

 have been replaced by the current miscellany of names, which furnish a clue 

 to the groups they embrace to the specialist only. 



'■* The necessity of this rule in dealing with the Briinnichian and Eafinesquian 

 genera (and some others) is obvious. 



