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Show 1879.] REV. O. P. CAMBRIDGE ON NEW ARANEIDEA. 279 P.S. Since the above has been in print, Mr. Sclater has received a further consignment of birds from Mr. Brown. Amongst these are three specimens of 31yzomclee, namely :-a female of M. sclateri; one of an entirely red species, probably = Ramsay's 31. coccinea or erythrina, the receipt of which will enable the necessary comparisons of these species with M. cruentata to be made ; and one of a species new to science. 5. O n some new and little known Species of Araneidea, with Remarks on the Genus Gasteracantha. By the Rev. O. P. C A M B R I D G E , M.A., C.M.Z.S., &c. [Received February 27, 1879.] (Plates XXVL, XXVII.) The Spiders described in the present paper are chiefly of the Gasteracantha, a genus well known and remarkable for the hard, horny epidermis of the abdomen, which is also armed with two, four, or six prominent spines, varying in length, strength, and direction, and issuing from different points of the margin. The abdomen is also marked on the upperside, and occasionally underneath, with numerous symmetrically disposed cicatricose spots, varying a little in number, size, form, and position. To these markings I have given, in the following descriptions, the name of sigilla, looking, as they do, very like seals impressed upon the abdominal surface. These sigilla probably indicate the points of attachment of muscular fibres, and are often useful in the determination of the species. The number of Spiders of this genus, described by various authors, up to the present time, is about 170; many, however, are already ascertained, and many more will in time probably prove to be, synonymous with others. At first sight it would seem to be an easier matter to distinguish the species of Gasteracantha than those of many other genera. They are for the most part of good size ; and the corneous, spiny abdomen, varying very much in its relative proportions and spines, furnishes characters so tangible that the species have for the most part been distinguished by these characters alone. No doubt these will always remain important characters, and in many instances decisive ones ; but in some, at all events, the reception of a series of examples from the same locality leads me to suspect that there is a very great, and hitherto not sufficiently recognized, difference in the absolute as well as relative length, strength, and direction of the abdominal spines in different individuals of the same species. Gasteracantha formosa, Vins. (infra, p. 285, PI. X X V L fig. 11), is one instance of this ; and G. curvispina, Guer., is probably another. Of this latter Spider (if I am right in my determination of the species) I have received a considerable series from the west coast of Africa ; but no two individuals preserve exactly the same length, strength, or direction of the abdominal |