Hancock. | 110 
[April 15, 1887. 
at extremity of tibia. Third pair of legs 42 mm., longest. Appendages on 
under surface pale whitish, of a horny consistence, fan-shaped and 
attached by foot stalks, ten in number, five on each side, two being adhe- 
rent to each of the first two, another to each of the third joints, first joint 
fixed, subtriangular, with base directed obliquely backwards and out- 
wards, equal in length to first pair of basal joints, second joint longer than 
the basal joint, third joint half the length of the second, fourth joint 
slightly longer than the third, swollen on under surface changing the 
direction of the leg slightly backwards, motion being confined to upward 
movement by first three joints (exclusive of the basal joint), fifth joint 
(femur) cylindrical and swollen, 10 mm., sixth joint (tibia) more slender, 
same length, cylindrical, seventh joint (metatarsus) 7mm. more slender, 
‘ eighth joint (tarsus) 34 mm., armed at extremity with two pale-colored 
claws, regularly curved, with sharp constricted points of red color. 
Abdomen. Composed of ten segments increasing in size to middle seg- 
ments which are 3} mm. long and 9 mm. wide, slightly decreasing in size 
posteriorly, first joint bears the genital opening on the under surface which 
is enclosed by an elevated plate of pale whitish horny substance, orifice 
triangular, apex directed forward, which is continued into a longitudinal 
slit, free from hairs, second and third segment each have on middle of 
posterior border stigmatic openings. The abdomen as a whole is oblong, 
oval, elliptic in form, convexed about equally above and below, slightly 
compressed, pale yellowish-white, clothed with velvet of pale whitish 
. hairs on both sides and under parts ; trace of broad longitudinal band on 
upper surface, more naked, beset with pale whitish hairs, band becoming 
narrower posteriorly, being 6 mm. wide at second joint ; under surface of 
abdomen slightly depressed by a median line, ventral opening a vertical 
slit 2 mm. in length on last segment, protected on both sides by narrow 
lips. 
Habitat, Laredo, Texas; taken in 1883. 
EXPLANATION OF PLATE. 
A. Datames magna Hancock, upper surface. 
B. Same, under surface. 
The following are magnified views : 
a, Side view of mandible showing finger and teeth. 
b. Front view of mandible showing position of secondary teeth, right 
side. 
c. Maxillary palpus, left side, under surface, showing spines. 
d. Labial palpus, left side, under surface. 
e 
f. 
. Last three joints of third leg. 
. Last three joints of second leg, showing spines on dorsal surface of 
metatarsus and tibia. 
g. Last three joints of first leg showing spines on dorsal and inner sur- 
face of metatarsus and tibia. 
. General appearance of claws under higher power of microscope. 
