734 MR. F. 0, PICKARD CAMBRIDGE ON [June 16, 
tibia iv. without any cusps or spines. Protarsus and tarsus iv. 
with a few spines beneath. Pedipalp. Femur and patella without 
cusps; protarsus and tarsus armed with numerous marginal cusps 
on either side. Tarsal claws three, on pedipalp one only, superiors 
armed with a small single denticle towards the base beneath. No 
scopula at all present. 
Spinners four ; posterior pair very short, less than one quarter 
as long as abdomen. Second joint half the length of basal; ter- 
minal half the length of the second. Anterior pair half the length 
of basal joint of posterior, one diameter apart, not closely con- 
tiguous. 
Comparative measurements in millimetres— 9. Carapace 7 long., 
6 lat. Abd. 9 long., 6 lat. Ceph. area 4 long. Coxa of pedipalp 
2°5 long., 1:5 lat. Stern. 4 long., 3:5 lat. Pedes, long. i. 17— 
ii. 15—iii. 16—iy. 21. Artl. i. long. 2:55—1—5—2—3—3. Artl. 
iv. long. 2°5—1—5:-5—2—4—3-5—2. Posterior mam. 2 long.; 
artl. 1—-5—-25, Ant. mam. ‘5 long., -25 apart. Mandib. 3 
long. 
A single specimen of the female sex was taken by myself 
amongst fallen mango-leaves in a clearing in the forest of Santarem 
in March 1896. 
Species already described from the Neotropical Region. 
Of the various species of Jdiops which have been already de- 
scribed from South America, some of them possibly belonging to 
the genus Acanthodon, the following appear to me to be quite 
different from A. santaremia. 
Idiops rohdei, Karsch (2 ), Berl. ent. Zeit. xxx. p. 93. 2, long. 
16mm. Hab. Paraguay ?—Although most of the characters given 
in this diagnosis are common to the whole genus, the statement 
‘“labio ad apicem irregulariter denticulato” certainly does apply 
to my species. 
Idiops fuscus, Perty (3), Delect. Anim. Art. 1833, p. 197, 
tab. 389. g. Hab. Piauhi, Brazil—The position of the eyes— 
“oeuli 8: 2 antici, 2 majores medii, et pone hos 4 in lineam 
curvam dispositi”—is not the same as in A. santaremia. 
Idiops argus, Sim. (9), Ann. Soc. Ent. Fr. 1889, p. 180. 
?,long.16mm. Hab. Venezuela.—The description of the labium, 
“ Pars labialis ad apicem spiculis 5-6 minuta,” clearly excludes my 
species, 
Idiops fulvipes, Sim.( 2), Ann. Soc. Ent. Fr. 1889, p. 181. 
2, long. 8 mm. Hab, Venezuela.—Of this species Simon says 
“ Precedenti valde affinis,” referring to J. argus, Sim.; and since 
he does not refer to the armature of the labium, one must infer 
that it is similar to that of the closely allied form. 
Idiops bonapartei, Van Hasselt, Tijdschr. Ent. xxxi. 1888, 
p- 166. 92, long. 14 mm. Hab. Surinam.—“ Labium serie 
transversa 7-denticulorum armatum.” A. santaremia has but 2. 
Idiops germani, Sim. (¢), Hist. Nat. Ar. 2nd ed, i. 1, p. 92 
