Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/309

THKLYPHOX1DS.] ARACHNIDA 289 maxilla, the inner fore corner of which is prolonged into a sharp, strong point ; the other joints are armed variously with teeth, and the final, or digital, joint in one species has a longish, but not very strong, spine beneath it, terminating with a small, apparently movable, curved claw. In these palpi we see a marked transition from the more apparent didactyle nature of those of Thelyphonides to those of the Phrynides, removing them further than the former, in this respect, from the Scorpiones. The leys appear very similar to those of Thelyphonus ; they are seven-jointed; those of the first pair are slender and evidently palpiforin ; their tarsi are composed each of several (apparently ten) minute articulations, and devoid of terminal claws. Those of the other three pairs are apparently inarticulate, and each ends with three simple curved claws, of which the inferior one is the smallest and most sharply bent ; the femora of these three pairs are all Btrong, those of the fourth pair inordinately so. The ster nal plates are very similar to those of Thelyphonus, but the hinder one is not so much developed, and the central corneous spot is not visible. This family, of small but exceedingly interesting blind Arachnids, contains but one at present known genus Nyctalops (Cambridge), and two species N. crassicaudata (Id.) and N. tenuicaudata (Id.); both are of a uniform pale yellow-brown colour, differing from each other, among other characters, in the markedly different form of the tail; the length of the largest (probably, but not certainly ascertained to be, in the adult state) is but 2| lines. They are found under decayed leaves in Ceylon ; but nothing is yet known of their habits, nor of their internal structure and anatomy ; analogy, however, points to a similarity in this latter respect to Thelyphonus. Family III. Phrynides. This is also a remarkably homogeneous family, and although, undoubtedly, a near ally of the Thelyphonides, yet in its form it presents many typical characters of the Araneidea (figs. 23, 24, 25). With respect to EXTERNAL STRUCTURE, the lody is short and broad instead of elongated, as in Thelyphonus and Nycta lops. The cephalo-thorax is flattened, of a round oval form, hollowed on the hinder margin, and often of a short heart or kidney shape; its integument is hard, horny, granulose, and often tuberculose ; near the centre is a deep fovea, or pit- like indentation, from which other grooves and indentations radiate, showing the, now soldered up, junctional lines of the caput and thorax, and thoracic segments. In these characters of the cephalo-thorax the affinity of Phrynides to the Araneidea is very plainly indicated, as it is also in the eternal plate, around which the legs are articulated. The f alces are strong and somewhat cylindrical in form. They project in a line parallel to that of the cephalo-thorax, and each terminates with a strong curved denticulated fang, which is articulated to its upper extremity. The falces are toothed also on their under sides ; the denticulations of the falces and their fangs differ a good deal in different species, and form one of the best and most tangible characters for the determination of the species (see a paper on "Phrynus," by A. G. Butler, in Ann. and Mag. N. II., Aug. 1873, pp. 117-125, pis. 6, 7). In the usual position are two strong divergent maxttlce, each with a broad obtusely rounded apophysis at the fore extremity on the inner side ; from the extremity of each maxilla springs along, strong palpus, in some species of great length, consisting of four or (reckoning the large terminal movable claw as a substan tive joint) five joints. This palpus is armed variously with tubercles, spines, and denticulations, especially on the cubital and radial joints, where several long, strong spines, opposed by the terminal claw (or digital joint), form a powerful grasping or raptorial organ, but one considerably further removed than the analogous portion of structure in Seal Flo. 23. Phrynus medius, Koch, a, a, movable fangs or claws on fourth Joint of palpi ; *, *, forming, with claws, c c, on third joint, modified didactyle claw ; ft, cephalo-thorax; d, falces; e, abdomen; /, button at end of ditto; ft. A, eyes; i, i, long palpiform legs. Thelyphonus from the didactyle claw of the Scorpionidea. Between the maxillae, and issuing from the fore margin of FIG. 24. Phrynut ? portion of under side, a, labium , 6, 6, maxilla ; c, sternum; d...d, orifices of respiratory organs; e, genital aperture. the sternum, is a narrow, elongated tapering labium, in some species bifid at its extremity ; the presence of a dis tinct sternal lip, or labium, is another mark of affinity to the Araneidea. The leys (seven-jointed) are long and generally slender, though the coxal joints of the three hinder pairs are long and strong, and arti- F IO . culated laterally to the sternum. fl The legs of the first pair are palpiform, and of great length II. 37 s. Faix and fane

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