32 
LYCOsnm 
Like other species belonging to the same genus, Lycosa fluviatilis, in constructing its cocoon, 
slightly connects the margins of the two compact portions beneath which the thin fabric of 
the zone is folded. This simple contrivance affords an admirable provision for the develop¬ 
ment of the young in the foetal state by an increase in the capacity of the cocoon consequent 
on the margins of the compact parts becoming detached by means of the expansive force 
within, the eventual liberation of the young being effected by the rupture of the zone, which 
is the weakest part. This interesting fact in the economy of the Lycosa appears to have 
escaped the observation of arachnologists. 
The specific name arenaria, given by M. Koch to this Lycosa, having been previously 
conferred on another species of the genus by M. Savigny, the trivial nam e fluviatilis is here 
substituted for it. M. Walckenaer has regarded this species as a variety of Lycosa vorax 
(‘ Hist. Nat. des Insect. Apt./ t. i, pp. 313, 314, and t. iv, p. 392), from which it differs in 
size, in the design formed by the distribution of its colours, and in its habits. 
Lycosa cambrica. PI. II, fig- 14. 
Lycosa cambrica, Blackw., Linn. Trans., vol. xviii, p. 614. 
_ _ Blackw., Annals and Mag. of Nat. Hist., second series, vol. vii, 
p. 396. 
Length of the female, §ths of an inch ; length of the cephalo-thorax, T 3 B tlis; breadth, l,ths ; 
breadth of the abdomen, £th ; length of a posterior leg, ^ths; length of a leg of the third 
pair, fths. 
The intermediate eyes of the anterior row are rather smaller than the lateral ones. The 
cephalo-thorax is large, glossy, and of a brownish-black hue; but it is clothed with yellowish- 
brown hairs, which are densest on the anterior part, and the sides and posterior part are 
marked with white hairs disposed in irregular spots. The falces are powerful, conical, with 
a few teeth and a fringe of long hairs on the inner surface ; the maxillae are strong, curved 
towards the lip, and are obliquely truncated and fringed with hairs at the extremity, on the 
inner side; the sternum is heart-shaped. The colour of these parts is brownish-black, the 
maxillae having a tinge of red at the extremity, and the sternum being thinly covered with 
long black, and short, yellowish-brown hairs. The legs and palpi are of a dark, yellowish- 
brown hue, marked with black annuli. The abdomen is rather broader at the posterior than 
at the anterior extremity, densely covered with hairs, convex above, projecting over the base 
of the cephalo-thorax; the colour of the upper part is yellowish-brown, a band of a paler hue 
extending from the anterior part, along the middle, more than a third of its length ; this band 
has an obscure border of black, on which there are several irregular white spots; a series of 
black and white spots, disposed alternately, commences near the posterior extremity of the 
band, on each side of the medial line, and extends to the spinners, where the two meet; the 
