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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 1 10 



(fig. 6 A) are leglike and have no association with the mouth; the 

 first legs are long and slender ; the relatively large, segmented ab- 

 domen terminates in a multiarticulate flagellum. The name Palpigradi 

 approximately expresses the fact that the palps are leglike and used 

 for walking; the name Microthelyphonida implies a resemblance to 

 the Thelyphonidae of the Order Pedipalpida in the possession of a 

 jointed tail, but otherwise there is no likeness between the two groups. 

 Though the second name antedates the other by a matter of two years, 

 the first is preferable for brevity and significance. 



Fig. 6. — Palpigradi. 



A, Koenenia mirabilis Grassi (from Hansen and Sorensen, 1897). B, same, 

 anterior end of body with mouth cone and detached left chelicera (from Hansen 

 and Sorensen, 1897). C, Prokoenenia wheeleri (Rucker), median section through 

 mouth cone and prosoma (outline from Rucker, 1901). D, Koenenia mirabilis 

 Grassi, prosoma and bases of appendages, ventral (from Borner, 1901). 



The structure of the palpigrades is known principally from the 

 work of Hansen and Sorensen (1897), Borner (1901, 1902), Wheeler 

 (1900), and Rucker (1901, 1903). The last two writers record 

 also something of the habits of Prokoenenia (Koenenia) zvheeleri 

 (Rucker). Wheeler suggested that this species, found in Texas, feeds 

 on the eggs of Campodea and Japyx, with which it is associated in 

 nature under stones where there is a sufficient degree of moisture ; 

 Rucker (1903) says that the alimentary canal contains nothing but 

 material resembling yolk particles, and is "admirably constructed for 

 such an illegitimate practice as egg-sucking," 



With respect to the feeding organs the Palpigradi are the simplest 

 of the arachnids. The relatively large, three-segmented chelicerae (fig. 

 6 B, Chi) arise at the base of a snoutlike cone bearing the mouth 



