A REVISION OF THE PISAURIDAE OF THE UNITED STATES 7 
DHE) PAMIEY  PISAWR DO AE 
Characters of the family. The characters enumerated below 
apply to the family as it is represented in faunal area under con- 
sideration: 
Cephalothorax longer than broad, somewhat constricted in the 
cephalic region; dorsal groove well defined, radial grooves less 
prominently marked; eyes eight, those of the anterior row noticeably 
smaller than the others except in Pelopatis and Thanatidius where 
they are almost equal; anterior row straight, recurved or procurved ; 
abdomen regularly oval (Dolomedes and Thaumasia), moderately 
long (Pisaurina), or long and narrow (Thanatidius and Pelopatis) ; 
spinnerets in a compact group at the end of the abdomen;; the pedicle 
short with its superior lorum composed of two median segments and 
a pair of accessory lateral sclerites; median segments united by a 
transverse suture in Pisaurina, the anterior segment notched behind 
to receive a projection of the posterior segment in Dolomedes, or 
as in Pelopatis, Thanatidius and Thaumasia, the anterior segment 
is gently rounded behind and fits the shallow excavation of the 
posterior segment. The relation of the median segments in the 
genera last named approaches the condition found in the genus 
Lycosa; but the lateral accessory sclerites are differently developed. 
In Lycosa, the lateral pieces are confined to the sides of the posterior 
median segment while in the pisaurids they extend along the sides 
of the anterior segment as well, sometimes, as in Pelopatis and 
Thanatidius, less than one-half its length or as in Thaumasia, its 
entire length. Corresponding to the general body development, the 
legs are relatively strong in Dolomedes and Thaumasia, less robust 
in Pisaurina, and long and slender in Pelopatis and Thanatidius ; 
tarsi provided with three variably toothed claws. Tibiae of the 
pedipalps of the males provided with an external apophysis. The 
structure of the palpal organ of a typical pisaurid may be under- 
stood by reference to the accompanying figure (1) on which (fol- 
lowing the terminology of Comstock) the parts are named. 
