. Il Cambridge storia naturale. Zoologia. Caratteristiche esterne 443. Fig, 231.-bocca-parti di Phalan- rjium. A, B, C, Gnathobases di pedipalp e prime e seconde gambe : ch, ohelioera ; ep, epistome; lab, labium ; m, moutli ; ped, pedipalp ; pre.ep, pre-epistome ; st, sterno, rappresentata dalla rimozione della parte anteriore del processo genitale, che si estende a linea tratteggiata ; 1, 2, 3, 4, gambe. è lungo e stretto nella Mecostetlii e Cyphophthalnii, ma nell'Plagiostethi, che includono la maggior parte delle forme trovati nelle regioni temperate, è molto breve e trasversale ed è nascosto da addominali

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. The Cambridge natural history. Zoology. EXTERNAL FEATURES 443. Fig, 231.—Mouth-parts of Phalan- rjium. A, B, C, Gnathobases of pedipalp and first and second legs : ch, ohelioera ; ep, epistome; lab, labium ; m, moutli ; ped, pedipalp ; pre.ep, pre-epistome ; st, sternum, shown by the removal of the anterior part of the genital process, which extends to the dotted line ; 1, 2, 3, 4, legs. is long and narrow in the Mecostetlii, and Cyphophthalnii, but in the Plagiostethi, which include most of the forms found in temperate regions, it is very short and transverse, and is hidden by the abdominal prolongation before mentioned. The anterior wall of the mouth is formed by a beak-like plate, the "epistome, " the basal portion of which is covered externally by a second plate, for which Simon ^ pro- poses the name " pre-epistome." In some Phalangids there are three little chitinous plates, one median and two lateral, on the clypeus, between the anterior border of the carapace and the insertion of the chelicerae. They are best seen in Nemastoma. The abdomen always presents evidences of segmentation, though there is a difference of opinion as to the number of segments of which it is composed. This is due to the already mentioned partial or complete fusion of the anterior segments with the cephalothorax. From the admirable researches of Hansen and Sorensen ^ it seems likely that the normal number of abdominal segments is ten. Ventrally, the abdomen is produced forward into a "sternal process" which is capped by a genital plate, hardly distinguishable in the Phalangidae, but readily visible in the other families, which surrounds and masks the unpaired genital orifice. Two stigmata or breathing pores are situated on the sides of the first ventral plate, which these authors consider to be composed of two fused sternites. As in other Arachnids there are six pairs of appendages articulated to the cephalothorax. They are the chelicerae, the pedipalpi,

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• bookcentury1800
• bookdecade1890
• booksubjectzoology
• bookyear1895