184 PROCEEDINGS OF THE NATIONAL MUSEUM vol, io8 



nostic for crassicutis in its present restricted sense. Wood's material, 

 borrowed from the Smithsonian Institution, was collected in southern 

 Mississippi. 



No further reference to the genus appeared until 1888, when 

 Charles H. Bollman recorded Fontaria crassicutis from Indian Springs, 

 Ga. 



In 1895, crassicutis was designated by O. F. Cook as the type species 

 of his new genus Pachydesmus, one of the six genera originally included 

 in Cook's family Xystodesmidae. 



The great monograph of the polydesmoids written by Carl Attems 

 and published in 1899 and 1900 contained the description of a second 

 member of the genus. Since Attems did not recognize Cook's new 

 genera, his species was proposed as Fontaria laticollis. The type speci- 

 men was said to have come from Illinois, doubtless through some 

 kind of error, as laticollis is known with certainty only from central 

 Tennessee, and no members of the genus have been found in or near 

 Illinois. 



In writing on miscellaneous American diplopods, Brolemann 

 (1900) published a good figure of the gonopods of crassicutis, from a 

 Louisiana specimen. Brolemann, as well as Attems, disregarded the 

 name Pachydesmus, preferring to retain the old usage of Fontaria 

 for most of the xystodesmid species. 



Thus, during the half century following the description of crassi- 

 cutis, only one additional species had been named, and less than half 

 a dozen references to them had been made in the literature. During 

 the very active career of R. V. Chamberlin, however, a considerable 

 number of new forms have been described, and in recent years several 

 other workers have dealt with the genus at least cursoril}^ Dr. 

 Chamberlin described Fontaria clara and F. louisiana in 1918, Pachy- 

 desmus retrorsus in 1921, P. duplex and P. incursus in 1939, P. si- 

 mulans and P. kisatchinsis in 1942, and P. denticulatus in 1946. 



In his final great treatise on the Polydesmida, Count Attems 

 (1938) accepted Pachydesmus as a valid genus, but combined with 

 it the genus Harpaphe Cook of the Pacific Coast region! Although 

 there is some similarity in the gonopods of the two genera, numerous 

 other characters prohibit any close association of them, much less 

 postulation of their identity. Attems included crassicutis, laticollis, 

 and intaminatus in his treatment of Pachydesmus, with retrorsus 

 added in the status of an "unsichere Art." 



Loomis (1943) recorded retrorsus from northeastern Alabama, 

 on the basis of material collected by Hubricht. In 1948, Loomis and 

 Hoffman placed Pachydesmus kisatchinsis Chamberlin in the synonymy 

 of Fontaria clara Chamberlin, bringing the latter name into Pachy- 

 desmus for the first time. Finally, Causey (1955) has recorded P. 



