50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 1 10 



(ecAp) parallel to the epistome (Epst), and is continued into the 

 narrow oesophagus (Oe). On the crest of each of the six radial 

 folds of the pharyngeal wall is inserted a row of dilator muscles (fig. 

 17 C). The dorsal muscles (did) have their origins on the epistome 

 {Epst) ; the lateral and ventral muscles {dll, dlv) arise on the epi- 

 stomal lamellae of the epistomo-coxal apodemes (ecAp). Circular 

 compressor fibers (cpr) alternating with the dilator muscles surround 

 the entire length of the pharynx. 



The dorsal wall of the pharynx of Phalangium opilio is shown by 

 Kastner to be traversed by a narrow median groove with sclerotic 

 walls (fig. 17 C, g). By contraction of the mouth region, Kastner 

 says, the anterior end of the pharyngeal groove is brought into contact 

 with the inner ends of the pseudotracheal canals of the pedipalp 

 endites. The canal system, therefore, evidently has some unified 

 function, though what this function may be is not known. It is of 

 interest to note that a dorsal pharyngeal canal is present also in the 

 Araneida (fig. igC, dc). 



The oesophagus is a narrow tube (fig. i6 H, Oe) going direct 

 from the end of the pharynx to the ventriculus (Vent). Just before 

 joining the stomach the oesophagus is slightly enlarged, but apparently 

 does not form here a sucking apparatus. According to Kastner the 

 oesophagus lacks dilator muscles, and the circular muscles end where 

 the tube enters the nerve mass. 



In their feeding habits the phalangiids appear to be exceptional 

 among the Arachnida in that they ingest fragments of their food as 

 well as liquid. Hansen and Sorensen (1904) say that "the middle 

 and anal divisions of the alimentary canal may be quite filled with 

 more or less digested portions of food, fragments of animals which 

 are easily recognized by the broken pieces of chitine which are con- 

 tained in them ; but such are never found in the diverticula." These 

 writers did not mention any particular species. Police (1927) says 

 that sections of Phalangium opilio show in the stomach only soft 

 material, though this may contain fragments of viscera and tracheae. 

 Tulk (1843) gives a rather fanciful description of the working of the 

 mouth parts during feeding, in which the oral endites are conceived 

 to be jaws for crushing the prey and extracting the juices, while a 

 further crushing function is attributed to the pharynx. The pharynx, 

 however, has no internal armature such as Tulk describes, and the 

 oral endites, though independently movable on the supporting coxae, 

 are too soft in texture to be masticatory organs. Though pieces of 

 the internal organs of the prey may be taken into the stomach by the 

 phalangiids, such fragments, according to Frank (1938), are dissolved 



