lyo Bryant Walker 



QUADRULA TRAPEZOID'S (Lea). 



Bariosta ponderosus Raf. is a synonym and Bariosta Raf. is a synonym 

 of Amhlema Raf., unless the species should prove to be generically distinct 

 according to Frierson (42, p. 7). 



FuscoNAiA UNDATA TRiGONOiDES "Frierson" Utterback. 



Fusconaia undata 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 (Bames). 



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

 Frierson and others. Vanatta states (140, p. 556) that the Amhlema 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 I^am. 



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 Q. perplicata 

 quintardii (Cragin). 



Genus TRITOGONIA Agassiz, 1852. 



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

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

 from the Digence of Simpson to the Tetragence. 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 Ouadrnla as proposed by him would seem to be inexpedient. 



Tritogonia tubErculata (Barnes). 



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

 Quadrula 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 Quadrula. If Rotundaria, with tuherculata Raf. 

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

 rula (Ortmann, 78, p. 116) ; but if not, the species would take the name of 

 ohesa ^\m-^. (Vanatta, Naut., XXIII, 1910, p. 102). 



Obliquaria 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. 



