64 PROCEEDINGS OF THE NATIONAL MUSEUM tol. no 



glacier in recent years, but spretus is the only species identified from 

 the remains imbedded in layers here and there in the glacier, and 

 sometimes conspicuous on the vertical face at the foot. Preserved 

 samples have long been supposed to be spretus, but during the period 

 when spretus was considered a migratory phase of mexicanus, and 

 before the critical features of the aedeagus were known, the samples 

 were not identifiable other than as mexicanus (as then called). Study 

 of the aedeagus of specimens now shows the samples in the U. S. 

 National Museum to be spretus; unfortunately, this had not been 

 done when the 1953 glacier paper was published. Prior to 1898, 

 grasshoppers were known to be preserved in the glacier, and they were 

 first examined and identified as spretus in 1914. The rather fragmen- 

 tary samples now at the U. S. National Museum represent 13 speci- 

 mens, from which two males taken in 1949 by Dr. J. R. Parker and 

 one taken in 1952 by Dr. Irving Friedman have been dissected and 

 found to be spretus. The dorsal valve of those males is well prer- 

 served and typical. Fragments of grasshoppers collected from the 

 central and bottom portions of the glacier in 1952 by Dr. Friedman, 

 of the U. S. Geological Survey, were sent by him to W. F. Libby, 

 then of the Institute for Nuclear Studies and Department of Chemis- 

 try, University of Chicago, for age determination by the carbon-14 

 method. Dr. Libby reported (in litt., Apr. 15, 1953) that the results 

 indicated an age of 45 ± 300 years and that the limits of error were 

 45 ± 600 years. He has since reported (Libby, 1954) the age as 

 45 ± 150 years. The specimens are thus indicated as quite modern, 

 and the likelihood is that the layers of preserved spretus are not more 

 than 200 years old, perhaps much younger. 



Various writers at about the turn of the century remarked on the 

 strange disappearance of spretus. Cooley's (1904a) experience of not 

 capturing a specimen during five years of collecting in all parts of 

 Montana was typical. Except for the Grasshopper Glacier material, 

 the only specimens collected since 1890 that we have examined are 

 from Clifford, N. Dak., 1891; Lincoln, Nebr., 1893; Delorain, Mani- 

 toba, 1898; "North Dakota," 1900; Larimore, N. Dak., 1901; Fairfax, 

 Manitoba, apparently 1901; Aweme, Manitoba, 1902. ^ Rehn and 

 Hebard (1906, p. 408) and Hebard (1928, p. 283; 1929, p. 390) recorded 

 three specimens (as spretus) which Hebard collected at Pike's Peak 

 and near Manitou, Colo., in 1904. The single male, from Pike's Peak, 

 on examination of the aedeagus, proves to be M. bilituratus bilituratus. 

 Thus, spretus is not known to have existed since 1902. 



Why spretus disappeared and whether it is extinct are unknown. 

 Riley, et al. (1883), included a long discussion by Lawrence Bruner, 



• All these latest records are represented by males. Aweme, where Norman Griddle lived and worked 

 for many years. Is near Treesbant, and about 15 to 20 miles southwest of Carberry, Manitoba. 



