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Show 1896.] SPIDERS FROM THE LOWER AMAZONS. 73l of the lateral posteriors and 1| a transverse diameter of the former from them. Taking another character-the spinulation of tibia i.: in some of these examples there are no spines, in some 1, in others 2 or 3; while in one case, tibia i. left side had 2 spines, tibia i. right side had none. The central anterior eyes are sometimes 2, sometimes 3 diameters apart; while the lateral anteriors vary greatly in their distance from the margin of the clypeus, in the immature being quite close \ Given, however, plenty of examples of each form, I have no doubt but that certain characters might be tabulated which would be broadly true of the various forms, but only then to be used with caution. Of the three forms-A. hartll, A. crasslpes, and A. wallacei-of which I have been able to compare the actual types, the form of the cephalic area furnishes a good differential character, while the spinulation of tibia i. furnishes another, and the form of the sternum a third. But of these species I have seen only five examples (females) of A. hartil and one (female) of A. crasslpes. I venture to think that no satisfactory conclusions will be arrived at until arachno-logists are willing to hand over all available material of a particular genus to some one or other who is prepared to take the trouble to thoroughly compare every specimen and tabulate the characters. At present there is confusion of tongues and hair-splitting disputation concerning the fraction of a difference in the distance between particular eyes, whereas the examination of a long series usually proves that these same disputed distances are themselves constantly variable quantities in the same form. The table given below will probably need considerable modification when a long series of forms is subjected to examination. A. Tibia i. with a series of 5-13 spines on inner side. 1. Anterior row of eyes a little wider than posterior.. A. caraiba, Sim. 2. Anterior row of eyes not wider than posterior. a. Tibia i. with 5-6 spines on inner side ; tibia ii. without spines on inner side A. scalops, Sim. b. Tibia i. with 9-13 spines on inner side; tibia ii. with 1-3 spines on inner side A. hartii, Poc. B. Tibia i. without any spines, or with 1-3 only on inner side. I. Central posteriors smaller than laterals. 1. Central posteriors scarcely smaller than laterals. a. Tibia i. witb three small spines on inner side. A. crasslpes, Keys. b. Tibia i. without any spines on inner side A. rojasi, Sim. 2. Ceutral posteriors much smaller than laterals... A. valencianus, Sim. II. Central posteriors reniforni, larger than laterals . A. wallacei, mihi. The characters of A. hartii and A. crasslpes have been taken from the types; the characters of the other species are taken from M. Simon's descriptions (Ann. Soc. Ent. Fr. 1889, pp. 176-177). They must, however, be used with caution. 1 Mr. Pocock has observed similar differences in the characters at different stages of A. hartii, Ann. Mag. Nat. Hist. ser. 6, xvi. p. 195. 47* |
