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Show 156 HEV. O. P. CAMBRIDGE ON THE GENUS IDIOPS. [Mar. 10, The spinners were hidden beneath the dense hairy covering of that portion of the abdomen. This fine and distinct species is described from a specimen in the British-Museum collection, received from the Swan River, Australia. In its general form and character it mostly resembles Idiops kochii (a native of South America); but it may readily be distinguished from all yet known species of the genus by the striking contrast of its colours. The specific name conferred upon it needs no explanation to those who are aware of Mr. John Blackwall's long and unwearied labours in the field of araneological science. IDIOPS THORELLII, n. sp. (Plate VIII. fig. 6.) Male adult: length 4\ lines; length of cephalothorax 2\ lines, breadth of cephalothorax 2 lines. The fore part (including the legs and palpi) of this Spider is of an orange-yellow-brown colour ; it is very sparingly furnished with hairs, and the legs have a few fine spines. The abdomen is dark yellow-brown ; the form of the cephalothorax is abroad but regular oval, depressed above ; the normal furrows and indentations are fairly marked. The eyes are seated in the normal position upon two tubercular elevations, as in Idiops meadii; the two which form the first row are the largest of the eight, and very near together ; they are situated close above the frontal margin, and form, with those of the second row, a narrow oblong figure, whose hinder width is the greatest; the two intermediate eyes of the hinder row are the smallest of the eight, and much further from each other than each is from the end one on its side. The falces are moderate in length and strength, and are armed with a group of strongish spines near their extremities on the upperside. The palpi are long and strong: the radial joint is very strong, longer than the cubital, and tumid behind ; it has a prominence on the middle of the outer side, armed with small tooth-like spines ; near the outer extremity of this joint is another piominence, smaller, but similarly armed: the palpal organs consist of a large, globular, corneous lobe, prolonged into a not very large, nor very long-pointed, curved, beak-like projection : the form of the maxillae and labium is normal; but the sternum is of a somewhat pentagonal form, moderate in size, and broader behind than before. The legs are moderate in length and strength ; their relative length is 4, 1, 2, 3 ; the tibiae of the first pair have two corneous projections near their extremities on the inner side; and each tarsus terminates with three claws, of which the two superior ones are pectinated, and the inferior one much the smallest. A single example of this species is in the British-Museum collection. Hab. South Africa. Its small size, as well as its colours and structure, will readily distinguish it from others of the genus. The specific name given to it is that of Dr. T. Thorell, Adj. Prof. Zool. Univ. Upsalae, and a distinguished araneologist. |