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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IIO 



since on its under surface are attached the recurved bases of the 

 cheHceral stylets (Sty) ; but for this same reason there can be no 

 question that it represents the united basal segments of the chehcerae, 

 as said by Becker (1935) and by Vitzthum (i940-'43, p. 809), and 



Phy Hst 3 



Fig. 29. — Acarina-Tronibidiformes-Tetranychidae, Tctraiiychiis. 



A, dorsal view of capitulum and anterior part of body, showing the united 

 cheliceral bases, or stylophore (Stphr), partly retracted beneath a marginal fold 

 of the dorsum (df) covering the spiracles (Sp) and the infolded anterior ends 

 of the peritremes (Ptr). B, diagrammatic interpretation of structure of feeding 

 organs of Tetranychws telarins (L.) based on a lengthwise sectional figure by 

 Blauvelt (194S, fig. 51), with parts somewhat separated for clarity of identifica- 

 tion with corresponding parts of other Acarina. C, cross section of rostrum 

 behind palps (from Blauvelt, 1945). D, cross section through stylet groove of 

 epistome over the pharynx (from Blauvelt, 1945). E, piece of a pseudotracheal 

 peritreme (from Blauvelt, 194S). 



therefore might be termed more appropriately the "cheliceral plate," 

 except for the fact that it is not a plate at all, but a thick lobe con- 

 taining an extension of the haemocoele. The word stylophore {Stphr) 

 suggests itself as a practical name. The rounded anterior surface 

 of the stylophore is abruptly declivous (fig. 29 B) and bears ventrally 



