46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 10 



Since there are no sternal plates on the prosoma of the Cyphoph- 

 thalmi, there is no under-lip structure closing the stomotheca below, 

 such as the sternum of the first-leg segment in Phalangiidae. When 

 the chelicerae are deflexed, however, their chelae are turned pos- 

 teriorly, upside down, close against the endites of the pedipalps and 

 the first legs ; in this position the pincers fit neatly between the ridges 

 of the first-leg coxae, and completely cover the stomotheca from 

 below. During feeding, therefore, prey held in the cheHcerae could 

 thus be applied directly to the cleft between the pedipalp endites, 

 through which the exuding juices might be drawn up to the mouth. 



The suborder Palpatores, or Plagiostethi, includes the familiar 

 long-legged phalangiids of the family Phalangiidae. The first full 

 description of one of these arachnids goes back to Tulk (1843), who 

 gives a detailed account of the external and internal structure of 

 Phalangium opilio L. Tulk cites earlier writers but says their work is 

 either superficial or lacking in detail. Among more recent papers those 

 by Police (1927), and by Kastner (1933a) on the feeding organs of 

 Opilio and Phalangiiiin are the most important. Since Police critically 

 reviews the work of others before his time, and gives numerous quo- 

 tations from their descriptions, the student historically interested is 

 referred to his paper. The following account of the phalangiid mouth 

 parts as developed in the family Phalangiidae is based on a species 

 of Leiohunum. 



A front view of the body of a phalangiid (fig. 16 B) presents a 

 most unusual appearance for an arachnid because of the number of 

 structures that are associated with the mouth, but which entirely 

 conceal it. Uppermost is the slender, tapering labrum {Lni) projecting 

 as a free lobe from an epistomal plate (Epst) between the pedipalp 

 coxae (IICx). Immediately below the labrum and converging beneath 

 it are the large, soft, endites of the pedipalp coxae (IIEndt), each 

 with a pair of accessory lobules on its base ; and beneath these endites 

 are the thick, padHke endites of the first pair of legs (IIIEndt). 

 Below all these structures, projecting like a broad under lip, is the 

 sternal plate of the first leg segment (II IS), which forms the floor 

 of the preoral cavity. Finally, projecting beneath the sternum are 

 seen the small, hairy endites of the second-leg coxae (IVEndt). 



The chelicerae of Leiohunum, as in all the Phalangida, are three- 

 segmented (fig. 16 A, Chi). The basal segments extend forward from 

 the anterior body wall above the epistome, the distal segments with 

 the relatively small pincers hang downward at the sides of the labrum. 

 The base of each chelicera is produced into the body as a large 

 apodemal extension from the lateral and ventral walls of the proximal 



