I70 Bryant Walker 



QuADRULA TRAPKzoiDKs (Lea). 



Bariosla pondcrosits Raf. is a synonym and Bariosta Raf. is a synonym 

 of Amhlema 1-^af., unless the species should prove to be generically distinct 

 according to Frierson (42, p. 7). 



FuscoNAiA UNDATA TRiGONOiDEs "Frierson'' Utterback. 



Piisconaia iindata trigonoides "Frierson" Utterback, Amer. Mid. Nat.. IV, 



191 5, p. 107, pi. XV, figs. 30A-D. 

 Type locality : Platte River, Agency Ford, Mo. 



QuADRULA UNDULATA (Barnes). 



This species has been identified as the Ainblcma costata Raf. by Conrad. 

 Frierson and others. A^anatta states (140, p. 556) that the Amblema costata 

 Raf. of the Ponlson collection is also this species. If identifiable from the 

 original description, Rafinesque's name would have priority. In consider- 

 ing this question attention should be given to the possibility that costata Raf. 

 may be the rariplicata Lam. 



Costata has been designated by Frierson (42, p. 7) as the type of 

 Amhlema Raf. 



QuADRULA UNDULATA PILSBRYI (Marsh). 



According to Utterback (135, p. 119) this is a synonym of 0. pcrplicata 

 q iiin tarda ( C ragin ) . 



Genus TRITOGONIA Agassiz, 1852. 



The recent discovery of Sterki ('07, p. 48) that in the type species, T. 

 tuherculnta, all four of the gills are utilized for marsupia, removes the genus 

 from the Digencc of Simpson to the Tctragencc. But in view of the re- 

 markable dimorphism of the species, which is apparently a sexual and not a 

 senile charcter as has been suggested by Ortmann, the subordination of the 

 genus to Oiiadnila as proposed by him would seem to be inexpedient. 



Tritogonl\ tubErculata (Barnes). 



Quadnila iritogonia Ortmann, Naut., XXII, 1909, p. loi. 

 Qnadrula parkeri Geiser, The Academician I, 191 1, p. 15. 



The new names proposed by Ortmann and Geiser can not be used, even 

 if the species is referred to Quadnila. If Rotundaria, with tuhcrculata Raf. 

 as its type, be given generic rank, Barnes' name can still be used in Qnad- 

 rula (Ortmann, y'^, p. 116) ; but if not, the species would take the name of 

 ohesa Simp. (Vanatta, Naut., XXIII, 1910, p. 102). 



ObliquarJa verrucosa Raf. is identified as this species by Conrad and 

 the shells so labelled in the Poulson collection are also that species according 

 to Vanatta (140, p. 554). If identifiable from the original description 

 Rafinesque's name has priority. 



