MYRIAPODA 55 



XYSTOCHEIR DISSECTA (Wood). 



Polydcsmus dissecfus Wood, Proc. Phila. Acad. Sci., p. 129, 1867. 

 Fontaria dissecta Bollman, Bull. 46, U. S. Nat. Mus., p. 123, 1893. 



Wood's original specimens were from Fort Tejon, Kern County, 

 California. It is not known whether they are still in existence, and no 

 recent collections from the same region have been studied. 



The generic affinities are obvious from the description of the gona- 

 pods, but it has seemed impracticable to identify the animals described 

 above with Wood's species, because the lower or lateral spine, instead 

 of being slender and nearly straight, is characterized as " broad, thin, 

 obtuse and as it were twisted on itself." 



Family CHELODESMID^. 



As at present constituted, this family extends throughout tropical and 

 temperate America, where it is richly represented in genera and species. 

 A few Asiatic species described under Oxyurus 1 also probably belong 

 to the same series, which is at present defined by negative rather than 

 by positive characters. The characters given in the following key 

 apply to all the species in the United States, but the alliances of many 

 tropical types are still very uncertain. 



ANALYTICAL KEY TO THE WEST AMERICAN GENERA OF 

 CHELODESMID.E. 



Gonapods very long, the anterior branch large and complex, with thin 

 crests and plates ; antennae longer than width of body. 



Genus Chonaphc. 

 1 Oxyurus jiavolimbatus L. Koch ( Abh. der k. k. zool. bot. Gesell. Wien, 1877, 

 p. 795, 1878) from Japan, Polydesmus {Oxyurus) cyprius Humbert & Saussure 

 (Verh. zool. bot. Ges. Vienna, xix, p. 6S4), and Oxyurus vestitus C. L. Koch 

 (System der Mjriapoden, p. 139, 1847). Of the last species I have examined 

 specimens belonging to the Berlin Museum, the same individuals studied by 

 Attems. They are generically distinct from the United States species commonly 

 referred to Leptodesmus, as well as from the Mexican type of this genus. The 

 6imple probe-like gonapod has been figured by Attems (Denksch. kais. Acad. 

 Wiss. math.-naturw. Classe, lxvii, p. 594, pi. vi, fig. 134, Vienna, 1898). Koch's 

 O. vestitus was the type of the genus Oxyurus. That this generic name was pre- 

 occupied was known to Bollman and other writers, who supposed, however, that 

 it could be replaced by Leptodesmus. This inference being incorrect, it becomes 

 necessary to rename Koch's genus Oxyurus, for which the term Melapke is pro- 

 posed, in allusion to the characteristic shape of the gonapod. The type of Me- 

 laphe vestita (Koch) came from Constantinople. It is also apparent from Attems's 

 figures that Mclaphc cypria (Humbert & Saussure) may be safely associated as 

 a 6econd species. Melapke differs from all the Chelodesmidae of the United 



