14 MEMOIRS OP THE CARNEGIE MUSEUM. 



Wisconsin (Call, 1885). This latter localitj' is doubted by Simpson, and I believe 

 that of all these localities only the Tuscarawas River is reliable. 



Outside of the upper Ohio region positive and trustworthy records arc absent. 

 Thus, for instance, this shell is missing in the Cincinnati Catalogue of Harper 

 (1896). Sterki's records from other parts of the state of Ohio are very vague. 

 Call (1896a) does not mention it from anywhere in Indiana, and so forth. The 

 Michigan record is founded upon Call's authority, and stands bj^ the side of another 

 one (Wisconsin), which is certainly in error. 



Apparently this form has been frequently' misunderstood, even by Simpson, 

 and this is the more probable, since corresponding, but not entirely identical, 

 forms are met with elsewhere. A flat form of F. subrotunda is found in Elk River, 

 West Virginia. This I have distinguished as var. leucogona (Ortmann, 19136, 

 p. 89), but in the lower part of this river the connection vf'iih typical subrotunda 

 recurs. 



All this tends to show that F. subrotunda has the tendency in the headwaters 

 of the Ohio to develop a fiat form, called kirtlandiana, constituting an ecological 

 race of the main species. I wish to call special attention to this; as we shall see 

 further on that similar phenomena present themselves to view in the case of other 



species. 



FuscoNAiA FLAVA (Rafincsque) (1820). 



Quadrula rubiginosa (Lea) Simpson, 1914, p. 872; Quadnda flava (Rafinesque) 

 Vanatta, 1915, p. 557; Fusconaia flava (Rafinesque) Utterback, 1916, 

 p. 26. 



Plate II, fig. 3. 



Records from Pennsylvania: ^^ 

 Clapp, 1895, p. 116 (Allegheny Co.)." 



Rhoads, 1899, p. 137 (Ohio Eiver, Coraopolis, Allegheny Co.)." 

 Ortmann, 19096, p. 199. 



Characters of the shell: Shell of medium size, but rather heavy. Outline 

 subtrapezoidal. Beaks not very prominent, and not inflated. Beak-sculpture 

 consisting of three to five subconcentric bars, slightly waved, forming an angle 

 upon the posterior ridge, and most distinct there. Often these bars are quite 



'- Marshall (1895, p. 90) quotes this species from the Mcgheny in Warren Co., but 1 consider this 

 an error. Just this instance (and a few others) induce me to question the accuracy of the locality of 

 some of the species recorded from Warren Co. I have repeatedly collected in this region, but (hd not 

 find any evidence for the existence of this form. 



" The localities in Allegheny Co. are in the region, where the transition from^am into Iriyuna takes 

 place. Some of Rhoads' specimens should be called flava. 



