54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IIQ 



trypsinlike proteinase, an aminopolypeptidase, a carboxypolypeptidase, 

 and a dipeptidase of varying strength. Lipase is strongly present, and 

 amylase in some cases, but probably a part of the amylase comes from 

 the prey. Since the several ferments are not found in the same 

 amount in all individuals, it is evident that the diverticula do not 

 secrete a uniform digestive liquid. 



The Mygalomorphae (Orthognatha) differ from the other spiders, 

 with respect to the feeding organs, in that the basal segments of the 

 chelicerae are directed straight forward from the body, and that the 

 pedipalp coxae, except in Atypidae, have only small, inconspicuous 

 anterior processes instead of the large jawlike lobes present in most 

 other spiders. As an example of the mouth-part structure in this 

 group a species of Eurypelnm, one of the "tarantulas" so called in 

 America, is here described. 



The pedipalps of Eurypehna hentzi Chamb. are smaller than the 

 legs ; in the female each appendage has six normal segments (fig. i8 C) 

 and a small, clawlike pretarsus (D, Ptar). The single elongate tarsal 

 segment is padded on the ventral surface with a thick, velvety coating 

 of small soft hairs (G, Tar), which distally form two apical lobelike 

 tufts. The pretarsal claw arises from a padlike surface on the end of 

 the tarsus (D), but is ordinarily almost concealed by the overhanging 

 hairs, only its tip being visible in the notch between the apical tufts 

 (G, Ptar). The claw is provided with the usual two pretarsal muscles, 

 a levator, arising in the tarsus, and a depressor, arising in the tibia 

 and patella with its fibers inserted on a long ventral tendon of the 

 claw. In the male, the pedipalp ends with a sperm-carrying organ 

 (fig, i8 E, Ptar), which clearly is a modified and specialized pretarsal 

 segment, since, as Barrows (1925) has shown, two muscles are at- 

 tached on its base, a levator {Ivptar) arising in the tarsus, and a 

 depressor {dp ptar) in the tibia. The legs differ from the pedipalps in 

 having two subsegments in the tarsus, and a pair of pretarsal claws. 



The pedipalp coxae lie horizontally in the plane of the leg coxae, 

 but they diverge anteriorly from the suboral sternum between their 

 bases. Their mesal faces adjoin the epistome, but are connected with 

 the latter only by membranous conjunctivae. In Eurypehna and most 

 of the other Mygalomorphae the pedipalp coxae have small anterior 

 processes at the inner sides of the trochanteral bases (fig. 18 C, F, 

 cxp), but in Atypidae (H) these coxal processes are large, thick 

 lobes {cxp) projecting beneath the chelicerae. 



The huge chelicerae of Eurypehna (fig. 18 A, Chi) project forward 

 but sag somewhat downward from the receding anterior wall of the 

 body, which seems scarce able to support them. The fangs turn back- 



