Produced by Chris Curnow, Joseph Cooper, Diane Monico, and the Online Distributed Proofreading Team at http://www.pgdp.net UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY Volume 11, No. 9, pp. 517-525, 2 pls., 1 fig. August 14, 1959 Description of a New Softshell Turtle From the Southeastern United States BY ROBERT G. WEBB UNIVERSITY OF KANSAS LAWRENCE 1959 UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson Volume 11, No. 9, pp. 517-525, 2 pls., 1 Fig. Published August 14, 1959 UNIVERSITY OF KANSAS Lawrence, Kansas PRINTED IN THE STATE PRINTING PLANT TOPEKA, KANSAS 1959 27-8360 Description of a New Softshell Turtle From the Southeastern United States BY ROBERT G. WEBB Examination of softshell turtles allied to _Trionyx muticus_ from the southeastern United States discloses the presence of an undescribed subspecies inhabiting river systems of the Gulf Coast. The author is indebted to Mr. Roger Conant for constructive criticism of the manuscript. I am grateful also to many fellow students for assistance in field work or for other courtesies, especially William E. Brode, Franklin Sogandares-Bernal, Ernest A. Liner, Donald W. Tinkle, Paul K. Anderson, and John K. Greer. The photographs were provided through the cooperation of Roger and Isabelle Hunt Conant and John M. Legler. Collections from which specimens were obtained are as follows: TU (Tulane University), USNM (United States National Museum), MCZ (Museum of Comparative Zoology, Harvard College), CNHM (Chicago Natural History Museum), KU (Museum of Natural History, University of Kansas), UI (Museum of Natural History, University of Illinois). Measurements (in millimeters) were made with a Vernier caliper and a metal tape; those of the holotype were made to the nearest one-tenth millimeter. Plastral length was measured from the posterior edge of the plastron to the anteriormost edge of the ventral surface; other measurements were maximal. Depth of shell was taken only on hatchlings and an immature female. Hatchlings were arbitrarily designated as specimens having plastrons shorter than 44 mm; sex of all specimens except adult males was determined by dissection unless otherwise noted. =Trionyx muticus calvatus= new subspecies Gulf Coast Smooth Softshell _Amyda mutica_ (in part), Stejneger, Bull. Mus. Comp. Zool., 94(1):23-24, 1944. _Amyda muticus_ (in part), Cook, Jour. Mississippi Acad. Sci., 1941-1947, p. 185, 1946. _Trionyx muticus_ Anderson, Copeia, 3:211, August 28, 1958. _Holotype._--UI 31071, hatchling, sex undetermined, from the Pearl River, Roses Bluff, 14 miles northeast Jackson, Rankin County, Mississippi; obtained by William F. Childers on August 25, 1952 (Plate 1).