230 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



shield and larger than the latter ; nearly all are barbed ; largest on 

 posterior body margin. Peritreme with lateral expansions at level of 

 coxae II-III and I-II; shape of posterior end distinctive; tubular 

 portion extends to level of anterior margin of coxae II. Epistome 

 relatively narrow, spikelike, with about 12 fimbriae on each lateral 

 margin; several fimbriae multiple. Chelae about equal in length: 

 movable chela may be slightly larger. Fixed chela with a bifid tip 

 and one tooth; an inflated seta immediately posterior to the tip; 

 a basal setae also present in most specimens. Movable chela with 

 a pointed tip and two teeth ; a faint, fringed bursa at its base. All 

 maxillary setae barbed. Corniculi narrow, pointed. Barbed setae 

 present on all palpal segments except tarsus; stout ventral setae on 

 coxae barbed. Most setae on all leg segments barbed; setae of legs 

 relatively long; longer and slenderer on dorsal surfaces of all seg- 

 ments. Length-width ratios of tarsi are : Leg 17:1, leg II 5 : 1, leg 

 1116:1, leg IV8:L 



Male. — Described from North American specimens. Dorsal shield 

 covers almost entire dorsal surface; setation and ]Dores as in female. 

 Dorsal body setae, tritosternum, and presternal area as in female. 

 Ventral shield widely expanded posterior to coxae IV, curving anter- 

 iorly lateral to coxae to contact lateral margin of posterior end of 

 peritreme ; anal region distinct. In most specimens accessory setae are 

 present as far anterior as level between posterior pair of sternal setae 

 and metasternal setae. Only anterior pair of sternal setae are barbed. 

 Pores as in female. Accessory setae larger and not so numerous as 

 those of dorsal shield ; much more numerous in some specimens than 

 in others. Accessory setae of anal region varied in number from three 

 to five ; in one specimen accessory setae were all posterior to coxae IV. 

 Peritreme as in female ; tubular portion may vary in length consider- 

 ably. Epistome as in female. Chelae show marked sexual dimor- 

 phism. Fixed chela toothless; with distal and proximal setae as in 

 female. Movable chela divided about midway on its length ; shorter 

 branch with a bifurcate tip. Maxillae and palpi as in female except 

 for sexual dimorphism shown on leg II, where stout ventral setae are 

 located as follows : femur two, genu one, tibia one, tarsus two. 



Nymph. — Described from North American specimens. Dorsal 

 shield much narrower than in adults; setae not so numerous as in 

 adults ; most are smooth ; dorsal pores not visible ; a slitlike invagina- 

 tion on each lateral margin of shield at level of coaxe IV. Tritoster- 

 num and presternal area as in adults. Ventral shield with sternal 

 and metasternal setae; pores located as in adults. Anal shield with 

 three usual anal setae and one smaller accessory seta in most speci- 

 mens; a few possess another accessoiy seta near anterior margin of 

 shield. Peritreme not well developed. Epistome, chelae, maxillae, and 



