8 University of Michigan 



Unto midtiplicatus Lea, '31, p. 70, pi. 4, f. 2. 

 U. hcros Say = U. midtiplicatus Lea, Conrad, '34, p. 69. 

 Quadrula heros (Say), Simpson, '14, p. 825. 

 Megalonaias heros (Say), Utterback, '16, p. 43. 

 Unio unduhtus Bar. = U. peruviana Lam. ('19) = U. giganteus Bar. 

 := U. heros Say, Frier son, 'i(fi, p. 63. 



U. undulatus Bar. t=C/. heros Say, Ortmann, '18, p. 539. 



"The original figures of Unio undulatus Barnes agree closely 

 with some broad examples compared by Pilsbry (also by 

 Frierson). In Barnes' figure the characteristic tuberculation 

 of heros would fall within the eroded area, the sculpture of 

 which was but slightly indicated by the engraver; but the 

 express statement of Barnes, 'Disks tuberculated below the 

 beaks,' cannot be ignored. The figures might represent either 

 heros or undulatus of authors {costa\tus Raf.), but the descrip- 

 tion is certainly decisive for heros. 



"Unio giganteus was included by Barnes in U. crassus, 

 which he described as waved. The only waved Unio seven 

 inches long occurring in the region of Prairie du Chien is U. 

 heros. 



"Probably the beak region was eroded and the tubercula- 

 tion thus escaped notice. In the absence of any other species 

 which fills the requirements, I believe with Frierson that 

 Megalonaias gigantea should replace M. heros." (H. A. P.) 



The view of Frierson that U. peruvianus Lam. is "almost 

 certainly" this species cannot be maintained. The figure in 

 the Encyclopedic cited by Lamarck is unmistakable. It has 

 swollen beaks, which are not in evidence in gigdntea, and no 

 other points in the description indicate this species. In fact, 

 peruvianus is the species generally known as U. plicatus Say. 

 See Amblema peruviana. 



