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Show 1870.] REV. O. P. CAMBRIDGE ON THE GENUS IDIOPS. 105 The labium was almost concealed; but it was apparently very small, though similar in form to that oi Idiops fuscus. Sternum somewhat oval in form, but much broader behind than before. Abdomen small, oval, very convex above, hairy, and of a dull yellow-brown colour, rendered blackish above by numerous bristly black hairs longer than the rest; the plates of the spiracles (four in number) are of a paler colour than the rest of the abdomen; the spinners are also four in number; those of the superior pair being much the longest and strongest, and biarticulate. An adult male of this Spider was received through Mr. Janson from Pebas (Amazons, South America) ; it seems to be nearly allied to Idiops fuscus (Perty), but is much larger, and differs both in the relative size and disposition of the eyes, as well as in the structure of the palpi. In connecting this species with the name of Dr. Ludwig Koch of Niirnberg, I desire to pay a slight tribute of respect to one of the keenest and ablest of living arachnologists. 3. IDIOPS SIGILLATUS, n. sp. (Plate VIII. fig. 2.) Male adult, length 9 lines. Cephalothorax broad, nearly circular, and depressed; caput short, as if truncated before, and its junction with the thoracic region marked by a deep, transverse, and somewhat curved indentation ; the other normal furrows and indentations are also pretty strongly marked ; the colour of the cephalothorax is a dark yellowish brown, and it is sparingly clothed with yellow-grey adpressed hairs, as well as some short black spiny bristles; a number of strongish black spines and spiny bristles also form a sort of border round its lateral margins. Eyes eight, placed on a black tubercular eminence of no great height, on the fore part of the caput; they are disposed in three transverse rows, 2, 2, and 4 ; those of the foremost row are the largest of the eight, near together, and situated immediately above the insertion of the falces; those of the second row are much smaller, and at some distance behind the former, with which they form an oblong rectangular figure, and occupy the summit of the tubercular eminence; not far behind these the four remaining eyes form the third row, which is much the longest and slightly curved (the curve directed backwards) ; the lateral eyes of this row are large, but rather less in size than those of the first row; the two central eyes are small (the smallest of the eight), and are further from each other than each is from the lateral on its side. From the centre of the rectangle formed by the eyes of the first and second rows, one or two strong, spiny, black bristles rise almost perpendicularly, curving a little backwards; two other bristles of the same kind, but shorter, spring up in a transverse line between the central eyes of the third row, and have their points directed forwards. Legs moderately long, strong ; relative length 4, 1, 2, 3 ; they are of a reddish yellow-brown colour, and are furnished with hairs, bristles, and black spines of varied length and strength: the tibiae |