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Show 102 REV. O. P. CAMBRIDGE ON THE GENUS IDIOPS. [Feb. 10, Mygalides. Subsequently M. Guerin-Meneviile (without any reference at all to the genus established by M . Perty) founded the genus Acanthodon upon another Spider, undoubtedly congeneric with that upon which the genus Idiops had been previously established (see * Arachnides du Voyage de la Favorite,' and ' Revue Zoologique,' 1838, p. 10). This genus, Acanthodon, was afterwards, in the Supplement to his history ' Des Arane'ides,' included in ' Ins. Apt.' torn. ii. p. 234, by Baron Walckenaer, who also seems to have overlooked its identity with Idiops. Since that time nothing appears to have been published upon it. The present occasion, therefore, seems a fit one for the re-establishment of M . Perty's genus, and the rectification of the erroneous reference to his species by Walckenaer in the work above quoted (Ins. Apt. torn. i. p. 379, where the specific name of Perty's Spider is also erroneously given as Idiops aculeatus, whereas the name given it in Del. An. Art. Bras, is Idioqjs fuscus). Of the species* which are now included in the genus Idiops, three (Idiops fuscus (Perty), I. kochii, n. sp., I. petitii (Guerin)), are from two widely separated localities in South America (Brazil and the Amazons); the fourth (I. sigillatus, n. sp.) is from the Swan River, West Australia, and in many respects a most remarkable species ; the fifth is from Beirut in Syria. Fam. MYGALIDES. Gen. IDIOPS. Idiops, Perty, Del. Anim. Artie. Bras. p. 197, 1830-34. Acanthodon, Guerin, Arachnides du Voyage de la Favorite, cl. viii. pl. 16. figs. 1-8 ; Revue Zool. 1838, p. 10; Walck. Ins. Apt. torn. ii. p. 234. Characters of the Genus.-Cephalothorax large, oval, in some species uniformly convex above ; in others the caput is more or less elevated, and the sides as well as the thoracic portion depressed. Eyes unequal in size and disposed in three transverse rows, 2, 2, and 4 ; this last row, the hindmost, is much the longest, curved, and not far behind the second, or intermediate row ; while the foremost one is placed at a considerable distance in front, and only just above the insertion of the falces; they may also be described (see Guerin, /. c. sup.) as disposed in two groups,-the first placed on the anterior margin of the cephalothorax, and composed of two eyes near to each other ; the second considerably behind and forming a longish narrow transverse oval figure, composed of six eyes. Falces strong, prominent, and generally armed at their extremities on the upperside with a group of short strong spines. Maxillee cylindrical, divergent, almost entirely destitute of any prominence on their inner extremities, so that (like many others of the Magalides) the palpus appears to spring from the very extremity of the maxilla. * Vide supplementary notice, in which other new species are described, postca, p. 152. |