1870.] REV. 0. P. CAMBRIDGE ON THE GENUS IDIOPS. 107 
wrinkles being sinuous, and with a longitudinal direction; each 
wrinkle is armed with a single and more or less complete row of 
short, strong, prominent, black spines; the hinder extremity of the 
abdomen has four largish, round, bare, black, slightly impressed 
patches, like seals; the two upper ones are the largest, and are 
wider apart than the two lower ones; the four form very nearly a 
square. The spinners (four in number) are short; the superior ones 
being the longest, strongest, and apparently biarticulate; the four 
spiracles are connected with conspicuous disks or plates of a reddish- 
brown colour, mixed with yellowish. 
An adult male of this very distinct and remarkable Spider was 
received through Mr. S. Stevens, from the Swan River, West Aus- 
tralia, in 1864. 
4. IDIOPS PETITII. 
Acanthodon petitii*, (Guérin-Méneville) Voyage de la Favorite, 
el. vill. pl. 16. figs. 1-8 ; Walck. Ins. Apt. tome ii. p. 234. 
Female adult, length 14 lines. 
Cephalothorax elongate-oval, contracted and elevated before, flat- 
tened on the sides and behind. 
Eyes eight, disposed in two separate groups; the first, situated on 
the anterior margin of cephalothorax, is composed of two large eyes 
very near to each other, and placed on a tolerably strong tubercle; the 
second group is much further back, placed upon a strongish eminence, 
and forming a very narrow, transverse, oval figure; this group con- 
sists of six eyes, the two hindmost ones being rather the smallest. 
Palpi long, strong, and pediform, almost as strong as the legs, 
and armed beneath with short, strong spines, forming a sort of rake 
(rdteau). 
Legs longish and strong; relative length 4, 1, 2, 3; those of the 
first two pairs armed beneath the two last joints with short, strong 
spines similar to those beneath the palpi; each tarsus ends with 
three claws, the two superior ones much curved, and armed beneath, 
towards their base, with a strong tooth; the inferior claw is much 
smaller than the superior ones. 
Falces prominent, and armed in front with a group of strong spines. 
Mazille and labium similar in form to those of Idiops fuscus. 
Abdomen oval, hairy, of a pale dull brown colour, with some 
largish yellow spots beneath, near the branchial openings ; the colour 
of the cephalothorax, legs, and falces is a lively chestnut-brown, 
shining, and as if varnished. Spinners four in number and unequal 
in size. Branchial openings four in number, and placed in the usual 
position beneath the fore part of the abdomen. 
Hab. Brazil. 
5. Iprops syrracus, n. sp. (Plate VIII. fig. 3.) 
Female immature, length 33 lines. 
The general colour of this species is yellow-brown, the cephalo- 
* Named after Dr. M. Petit de la Saussaie, by whom it was discovered and 
presented to M. Guérin. 
