SYNOPSES OF NORTH-AMERICAN 
INVERTEBRATES. 
IX. THE Scorpions, SOLPUGIDS, AND PEDIPALPI. 
NATHAN BANKS. 
TuEsE three groups belong to that order of the Arachnida 
known as the Arthrogastra. It may be separated from the 
other arachnids of the United States, and practically of the 
whole world, in the following manner: 
Abdomen plainly segmented, palpi of male not modified for a genital organ, 
rarely of small size,-no jointed abdominal spinnerets Arthrogastra 
Abdomen not plainly segmented, joined to the cephalothorax by a slender 
pedicel, palpi of male modified for a os organ, at least one pair 
of jointed abdominal spinnerets. . Araneida 
Abdomen not plainly segmented, broadly mied é to EIE R no jointed 
spinnerets, male palpi not modified, of small or even minute size 
Acarina 
The three groups of the Arthrogastra treated in this paper 
are easily distinguished by the following characters : 
1. Abdomen ending in a poison sting, base of abdomen beneath bearing 
a pair of appendages with teeth (pectines) ; palpi chelate at tips, 
legs without patelle ; porian part of abdomen much narrower than . 
the anterior part . . . » Scorpionida 
Abdomen not ending in poison sing ; no peclaes palpi not chelate at 
tips 2 
2. Hind coxe heated a ie T: ‘taped PT hind noba of two 
segments, no sternum, no patelle in any legs . . . . Solpugida 
Hind coxz without such appendages, hind trochanters not biseg- 
mented, patellz in at least some of the legs ; sternum often present, 
ody considerably constricted between cephalothorax and abdomen 
Pedipalpi 
PEDIPALPI.! 
The Pedipalpi are ere dinem so that there is but a 
E] 
meri ican Naturali ist will undertake 
be cannot be placed i in the keys, and Haw corrections and criticism fer Pulvis 
ision. 
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