NO. 10 



FFEDING ORGANS OF AKACH NIPA— ^SNODGRASS 



57 



attached a large dilator muscle (B), tlie fibers n{ which spread from 

 their origins on the epistome (Ilpst). 



The relatively weak, concave ventral plate of the pharynx (fig. 

 19 E) is longer than the dorsal plate because the edge of the pedipalp 

 sternum (US) extends beyond the labrum. The median part of this 

 plate, or ventral wall of the pharynx, is hut weakly sclerotizcd except 

 for a strong bar, deeply forked at the upper end, that traverses its 

 middle. On the inner end of the ventral plate is inserted a pair of 

 large muscles from the prosomatic carapace (l'>). 



Lm 



Mth 



Fig. 19. — Araneida-Mygalomorphae, Eurypehna hentzi Giamb. 



A, chcliccral fang and venom gland. R, longitudinal section tlirough mouth 

 region and pharynx. C, dorsal plate of pharyn.x and lower end of labrum, 

 ventral. D, cross section of dorsal plate of pharynx. E, ventral plate of pharynx 

 and distal end of pedipalp sternum, dorsal. 



The mouth parts of the Dipneumonomorphae (Labidognatha), or 

 ordinary spiders, difTer from those of the Mygalomorphae principally 

 in that the chelicerae hang downward from the anterior edge of the 

 prosoma (fig. 20 B), and that the pedipalp coxae have large lobes 

 at the sides of the mouth which give the appearance of a pair of 

 strong jaws (C, D, cxp). These coxal lobes of the spiders have no 

 independent movement, since they are solidly affixed to the coxae. 

 In appearance they suggest the coxal endites of the Phalangida, but 

 inasmuch as they arise from the distal ends of the coxae, and in 

 some forms, as in Dysdcra crocata C. Koch (G), they are no different 

 from the large coxal processes of the mygalomorph .Itypus (fig. 

 18 H), it is clear that they are nu-rcly special developments of the 



