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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 110 



long, three-segmented, and chelate (fig. 24 C, Chi). Each chelicera 

 is invested in a membranous sheath (ChS) inflected from the distal 

 end of the tectum and the inner end of the epistome, and then re- 

 flected forward in a fold that again turns back within itself to the 

 distal end of the basal segment of the contained chelicera. 



The diagram here given (fig. 24 C) is a free translation of the es- 

 sential structure in Winkler's sectional figure of a male nymph of 

 Poecilochirus carabi Cn. Below the chelicerae are the epistome 

 {Epst), termed the "intermaxillary Chitingeriist" by Winkler, and 

 the elongate labrum {Lm). The labrum ("Zunge"), Winkler says, 

 is movable up and down, and also retractile by muscles inserted on 

 its base, and is pressed like a wedge into a groove of the hypostome. 



Fig. 25. — Acarina-Gamasides. 



A, Parasitus crassipcs (L.), female, capitulum and first body segment, ventral 

 (from Winkler, 1886). B, same, male (from Winkler, 1886). C, Laclaps 

 cchidninns Berl., capitulum, ventral (from Stanley, 1931) ; m, p, coxal processes 

 associated with the hypostome. 



The under surface of the capitulum is prolonged beyond the mouth 

 into a hypostomal under-lip structure (fig. 24 C, Hst). In Parasitus 

 crassipes (L.) figured by Winkler (fig. 25 A, B) the hypostome pre- 

 sents a median lobe fringed with long hairs, which is much longer in 

 the male (B) than in the female (A), and bears on each side a slender 

 process (/>) and a small lateral lobe supporting a knifelike or scalpel- 

 shaped process (w). These hypostomal details, Winkler says, show 

 much variation in different species. 



