keletons in the University of Kansas Museum of Natural History demonstrate occurrence of the condition in at least 3 American species: Amyda emoryi (Agassiz), A. mutica (Le Sueur) and A. spinifera (Le Sueur). The specimen of A. emoryi (Catalog No. 2219) was taken at Phoenix, Maricopa Co., Arizona, by Victor H. Householder, on May 1, 1926. The second specimen, called to my attention by C. W. Hibbard, was taken in 1936 from the Kansas River at Lawrence, Douglas Co., Kansas, by Max Wheatley, to whom I am indebted for the accompanying photographs and permission to describe the specimen which he has added to the Museum's collections (No. 23230). The identity of No. 23230 is established as A. mutica by the absence of spines (see fig. 3) and by a number of cranial characters. The specimen of A. spinifera (No. 23026) is without locality data; its identification is verified by the presence of spines on the front of the carapace.
In the specimen of A. mutica (see figures) the hump forms a smooth, high curve, closely resembling the condition in Gressitt's specimens of A. steindachneri