Mr. J. Blackwall on new Species of Spiders. 211 
Apt. tom. ii. p. 291) is a much larger spider than the T. triste 
of Hahn and Koch, and is probably specifically identical with 
the Phrurolithus lunatus of the latter author (Die Arachn. 
Band vi. p. 107, tab. 206. fig. 509). 
Theridion grossum. 
Theridion grossum, Walck., Hist. Nat. des Insect. Apt. tom. ii. p. 328. 
Theridium grossum, Koch, Die Arachn. Band. iv. p. 112, tab. 140. fig. 321. 
Length of the female 2 of an inch; length of the cephalo- 
thorax 3, breadth 4; breadth of the abdomen ;3,; length of an 
-anterior leg 2; length of a leg of the third pair ;%,. 
As the adult female of Theridion grossum, which, like certain 
species of the genus Latrodectus, does not acquire its sombre 
hue till it arrives at maturity, has been well described by Koch, 
I shall merely supply, in addition to the measurement given 
above, a few particulars that have been omitted. 
The eyes are disposed on the anterior part of the cephalo- 
thorax in two transverse rows; the four intermediate ones de- 
scribe a trapezoid, the two anterior ones, which form its shortest 
side, and are seated on a protuberance, being the smallest and 
darkest-coloured of the eight; the eyes of each lateral pair are 
placed obliquely on a tubercle and are contiguous. The maxille 
are obliquely truncated at the extremity, on the outer side, and 
inclmed towards the lip, which is somewhat quadrate, being 
broader at the base than at the apex. These parts have a red- 
dish-brown hue, that of their extremities being yellowish-white. 
The sexual organs, which are well-developed and semicircular, 
have their posterior margin curved and prominent, and are of a 
red-brown colour, that of the branchial opercula being dull 
yellow. 
The immature female and adult male of this species do not 
appear to be known to arachnologists. They differ remarkably 
from the adult female, the upper part of the abdomen being of 
a dull yellowish-white hue, densely freckled with minute white 
_ spots, and having a series of broad, curved, transverse, soot- 
coloured bands in the middle, whose extremities extend to the 
sides. The legs have a brownish-yellow hue. 
The male is much smaller than the adult female, and its 
slender legs are much lighter-coloured. Its palpi are short, and 
the radial, which is larger than the cubital joint, is produced at 
its extremity, on the outer side; the digital joint is of an elon- 
gated oval form and of a reddish-brown colour ; it is pointed at 
the extremity, convex and hairy externally, concave within, 
comprising the palpal organs, which are well developed and are 
terminated by a large curved spine, whose extremity is in con- 
