28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 10 



are dorsal in the Pedipalpida (tigs. 8 B, 9C). Below the chelicerae 

 is a broad horizontal surface formed of a median epistomal plate 

 (fig. 9B, Epst) flanked by the large dorsal plates of the pedipalp 

 coxae (dplcx). The epistomal plate is divided by a median groove, 

 and from its end projects the elongate, tapering, hairy labrum (Lm) 

 between the setigerous mesal surfaces of the anterior processes of 

 the pedipalp coxae {cxp ) . At the base of the epistome there extends 

 into the body cavity a strong apodemal arm (B, D, eAp), which, as 

 shown by its muscle connections, is clearly the epistomal apodeme 

 of other arachnids, though in the Thelyphonidae, as noted also by 

 Pocock (1902), it is not connected with the base of the epistomal plate 

 ("clypeus" of Pocock), but arises from the body wall just above the 

 epistome. 



The pedipalp coxae present ventrally broad, flat surfaces (fig. 9 A, 

 IICx) in contact with each other for most of their length, there being 

 no evident remnant of the deutosternum between them. Anteriorly, 

 however, the coxae are produced into a pair of thick, widely divergent, 

 triangular processes projecting mesad of the trochanters. The dorsal 

 surface of each coxa, as above noted, contains a large plate (B, dplcx) 

 united mesally with the epistome, and continuous anteriorly into the 

 coxal lobe {cxp). Laterally the coxal plate bears the dorsal articu- 

 lation of the trochanter (Tr), but behind the trochanter it is separated 

 from the sclerotic lateroventral coxal wall by a membranous gap, and 

 its posterior mesal angle is produced into a tapering apodemal process 

 (B, D, E, cAp). The united parts of the pedipalp coxae of Mastigo- 

 proctus extend beyond the tip of the labrum (B), and form under 

 the latter a deep trough {PrC), the lateral walls of which are mem- 

 branous and densely clothed with hairs converging downward beneath 

 the labrum. The cavity thus enclosed is the anterior, open part of a 

 preoral food passage leading back to the sucking organ. The posterior 

 part of this passage has a highly specialized type of structure not 

 known in any other group of arachnids. 



The ingestion apparatus of the Thelyphonidae has been described 

 by several writers, including Bernard (1893), Borner (1901, 1904), 

 and Kastner (1932a), but it is most clearly portrayed by Pocock 

 (1902). At the inner end of the open cavity between the labrum 

 and the trough of the united pedipalp coxae is a semicircular slit 

 concave dorsally. From this slit there continues posteriorly a semi- 

 cylindrical crevicelike passage (fig. 9 G, PrC) between a ventrally 

 convex dorsal plate, or lamina dorsalis (Imd), and a dorsally concave 

 ventral plate, or lamina ventralis (Imv). The dorsal plate is the under 

 wall of the labrum (Lm), the ventral plate is a continuation from 



