1875.] NEW SPECIES OF ERIGONE. . 191 
that very many more remain to be discovered; and the number of 
curious and distinct conformations of the caput in the male would 
seem to be almost without limit. It is probably from the several di- 
stinct types of this portion of the structure that it will be found some 
day most practicable to break up the genus into subordinate groups. 
While, however, the males may be thus grouped, it appears as yet 
that the females do not follow the same laws of development in re- 
spect of the caput, the structure of that part in the female affording 
frequently no evidence at all of affinity to the male; hence arises the 
great difficulty, in very many cases, of deciding to which species the 
females belong; for it often happens that any one of several females 
may, as far as structure and colour are concerned, be, with equal 
propriety, relegated to one male. It is not difficult to distinguish 
the different females among themselves, since each ordinarily possesses 
strong specific characters ; but their general similarity of form makes 
it exceedingly difficult to propose any method of grouping them. 
ERIGONE RETROVERSA, sp.n. (Plate XXVII. fig. 1.) 
Adult male, length 14 line. 
The cephalothorax of this very distinct species is of a dull 
greenish olive colour and of a rather flattened form, the caput and 
thorax being nearly on the same level, and the normal grooves and 
indentations indistinct ; the height of the clypeus is not quite two 
thirds of that of the facial space. 
The eyes are of moderate size and not very unequal in their rela- 
tive magnitude; they are seated on the fore part of the caput, which 
projects slightly forwards, in two transverse rows or four pairs some- 
what elosely grouped ; those of the hinder row are about equidistant 
from each other, those of the fore central pair, which are the smallest 
of the eight, are rather nearer together than each is to the fore lateral 
eye on its side. 
The legs are of a pale yellow colour, the tibiz of the first and second 
pairs being dark olive-brown; they are long and strong, furnished 
with hairs and a few nearly erect slender spine-like bristles. 
The palpi are short: the cubital and radial joints very short, but 
of about equal length ; the former is somewhat subangularly promi- 
nent on its upperside, where it has a strong, black, tapering bristle ; 
a similar but longer and stronger bristle springs from the upperside 
of the radial joint, which enlarges at its extremity, but has no pro- 
minences or projections: the digital joint is of a dark yellowish brown 
colour, and has its hinder extremity produced into a long, very strong 
and slightly tapering projection, which curves back towards the 
cubital joint ; the length of this produced part is equal to that of 
the joint, and its extremity is somewhat squarely truncated and of 
a blackish colour; near the extremity, on its outer edge, is a strong, 
black, sharp pointed corneous prominence ; and below this again the 
digital joint has a large curviangular prominent lobe; the palpal 
organs are well-developed, prominent, and complex. 
The falces are long, strong, and a little inclined backwards; they 
are similar in colour to the cephalothorax. 
