62 ARANEIDEA. ~ 
This remarkable spider may easily be distinguished by its long, narrow, caudiform 
abdomen. 
Acrosoma calcaratum, sp. n. 
Adult male, length 24 lines, length of the abdomen 14 line. 
The cephalothorax is of a deep bistre-brown colour, very glossy. The normal grooves and indentations are 
slight, the central portion of the ocular region is rather produced forwards, and the posterior margin is 
truncated and curved upwards. 
The eyes of the central group form a quadrangular figure whose posterior side is rather longer than the 
anterior. 
The legs are slender, moderately long, 4, 1, 2,3. The fore sides of the femora of the first, second, and fourth 
pairs are granulose ; the third and fourth pairs are dark yellowish-brown ; the femora of the first and second 
pairs, as well as the undersides of the tibia and metatarsi, are similar in colour to the cephalothorax, the 
other portions being yellowish-brown. They are furnished with hairs, but are destitute of spines. 
The palpi are short, the palpal bulb large. The digital joint has a short, curved, obtusely pointed process at 
its base on the outer side. The palpal organs are very prominent and highly developed; two long, 
strong, contiguous, corneous processes extend from their fore extremity rather backwards, and at their 
base on the outer side there projects a spiny process, one of whose limbs forms a longish, curved, horn-like, 
not very sharp pointed spine. There are also other spines and processes connected with these organs. 
The sternum is of a subtriangular form and granulose, with marginal eminences near the articulation and a 
strong transverse impression near the hinder extremity of the legs (in respect to the articulation of the 
latter there is the same peculiarity in A. parallelum and other species). 
The abdomen is articulated to the thorax by a short but distinct pedicle ; it is half as long again as the cephalo- 
thorax, narrow (equal to the width of the hinder part of the thorax) in front, and enlarging gradually 
to rather more than double the breadth at its hinder extremity, which is deeply indented—it is thus of 
an elongate-triangular form. The upperside is black and glossy, with narrow yellowish-white lateral 
and posterior margins; in the centre is a dull yellowish, suffused, slightly tuberculose spot, and midway 
between it and the hinder margin are two larger, round, yellowish-white, well-defined tubercular spots 
near together, but not contiguous, in a transverse line. The lateral margins of the abdomen are some- 
what sinuous, indicating suppressed eminences, which in the female may very probably be represented by 
distinct prominences or spines; each corner of the hinder extremity has a group of several small tuber- 
cular prominences. The spinners are in a strong, prominent, sheath-like prominence, and situated about 
one third of the way from the hinder extremity towards the fore end. The underside is dark yellow- 
brown and strongly rugulose. 
Hab. Panama, Bugaba (Champion). 
A very distinct species. 
Acrosoma brevipes, sp. n. 
Adult male, length 13-2 lines, length of the abdomen 1-14 line. 
This spider may easily be distinguished from A. parallelum by the dark olive-brown, uniformly glossy cephalo- 
_ thorax; the shorter and more slender legs, which are devoid of spines; the abdomen much less flattened 
in form, and narrower before, and enlarging gradually to the posterior extremity, where it is bluff and 
truncated; and the spinners prominent and placed nearly midway between the fore end and the hinder 
part. 
The legs are 4, 1, 2, 3, dull yellowish-brown behind, but much darker in front. 
The palpi are somewhat similar in general structure and appearance to those of .A. parallelum, but the palpal 
bulb is rather smaller ; the production at the base of the digital joint has its end strongly hooked, with a 
prominent though bluntish point behind the crook, giving it a bifid appearance. The radial joint is also 
bifid at its anterior extremity, being produced into two sharp corneous points. The palpal organs have 
