MARPISSA. 249 
‘it was selected by Thorell in 1870 for Marpissa, C. L. Koch. ‘The structural characters 
are shown on our Plate [Tab. XXI. figg. 17, 17 a—c, 2 ]. 
_ The Central-American species known to me may be recognized as follows :— 
Males. 
I. Abdomen grey-white, with a narrow longitudinal dorsal central brown 
band, resolving into three or four brown chevrons above the spinners. 
(Bulb simple, without any prominent tooth or spur in the centre. 
Apical spine stout, straight, slightly curved at the apex. Tibial 
spur of palpus very slight, scarcely noticeable.) . . . . melanognatha, Lucas. 
II. Abdomen black, with a broad more or less dentated or scalloped 
longitudinal dorsal central white or pale band. 
A. Apical spine of palpal bulb bifurcate . . . . . . . . . . . familiaris, Hentz. 
B. Apical spine of palpal bulb simple. 
a. Tibial spur of palpus very conspicuous, stout, curved, pointed at 
the apex, with a stout conical spur near its base beneath the 
segment. Bulb enlarged, with a stout anterior central spur, best 
seen in profile. Apical spine much larger, stout at the base, 
strongly curved, aculeate at the apex. . . . » . . . magna, Peckh. 
6. Tibial spur of palpus long, slender, slightly curving - downwards. 
Bulb not so greatly enlarged, without a central spur, but with a 
slight inner basal cusp. Apical spine much smaller, stout, and 
curved . . 1 we ee ee ee ee ee ee INET, SP. DL 
Females. 
I. Abdomen grey-white, with a narrow longitudinal central brown band, 
resolving into three or four brown chevrons above the spinners. 
(Vulva consisting of a large triangular-oval area having two elongate 
cavities on each side of a central carina, narrow in front, broadly 
dilate behind, where on each side is situated a dark orifice.) . . melanognatha. 
II. Abdomen black, with a broad more or less dentated or scalloped 
longitudinal dorsal central white or pale band. 
-°], Vulva consisting of a large triangular-oval area, having near its 
anterior margin a transverse oval concavity, whose posterior inner 
margin is deeply indented in the middle; and a pair of circular 
adjacent dark spots near the posterior margin of the vulval area, 
which is itself scalloped in the middle . . . . . . . . « . «magna. 
2. Vulva without anterior transverse oval concavity. 
' q. For vulvasee Plate . . 1. 1 ee ee ee ee ee we familiaris. 
b. For vulvasee Plate... 1 ee ee ee ee ee ee melanura, sp. n. 
Nors.—I do not know M. familiaris, and cannot therefore describe the vulva in comparative diagnosis with 
that of M. melanura. The species are, however, obviously quite distinct and will not be confused, with 
-Peckham’s figure of the vulva of the former as a guide. 
BIOL. CENTR.-AMER., Arachn. Aran., Vol. IL, September 1901. 2 xt 
