HANSEN AND SÖRENSEN, THE TARTARIDES. 7 



ra bly concave, the posterior margin a little emarginate a t the 

 niiddle; the plate is as broad as the posterior part of the 

 liead and separated from it by a rather long membrane in 

 which the plates of the first tergite just described are seen. 

 In Trithyreus the tergite is divided either by a median narrow 

 strip of more or less membranous skin without reticulation 

 or at least by a sharp median suture which is easily seen by 

 a powerful pocket-lens when the upper surface is dry. In some 

 cases it is very difficult or perhaps impossible to decide 

 whether the suture does not allow special flexion or it has 

 thinner skin than the surrounding tergite, so that special 

 flexion — of course indirectly produced — is possible; the 

 latter condition is a transition-stage to the existence of a real 

 membranous strip. In Schizomus the tergite is undivided, 

 without any suture, and equally reticulated on the whole 

 surface; especially in S. Simonis it has apparently a lighter 

 stripe along the middle, but when the surface of the tergite 

 is dry an inspection will show that the stripe is only due to 

 the fact that a whitish or light yellowish middle portion of 

 the contents of the thorax shines through the skin^ 



It may be considered superfluous to give here for com- 

 parison with the Tartarides a description of the dorsal side. 

 of cephalothorax in Oxopoei. We shall only point out that 

 the common statement of three eyes in each lateral group is 

 not correct; it is, however, still found in papers as Kraepe- 

 lin's monograph and Pocock's above-named work on Indian 

 Arachnida, both published a few years ago. In 1886 Marx- 

 discovered two small additional eyes in each lateral group in 

 Jlastigoprocttis gigantens Lucas; in 1893 Hansen pointed out 

 the existence of two similar small eyes besides the three 

 easily observed in Thelypkonus sepiaris ButL; in Hypoctonus 

 rangunensis Oates we have found the same number, and we 

 t hink therefore that five eyes in each group are present in 

 all Oxopoei. 



^ Kraepelin' who had seen a specimen of the species on wliich Cook 

 estal)lished. his genus Artacarus, had i-efem^ed it to Schizomus tenuicaudatus 

 Canibr. Therefore we suppose that when Cook writes on ^4?-tocart<.'?.' »Suture 

 of posterior part of cephalothorax chitinized», tliis »suture» is in reality 

 only a light stripe beneatli tlie skin. In Chapter IV it will be shown 

 that Artacarus must be cancelled. 



- Marx, G.: Notes on Thelyphonus Latr. (Entonioiogia Americana, II. 

 X. 2, 1886. p. 38—40). — Quoted after Ph. Bertkau's Bericht iib. d. wis^. 

 Leist. ... d. Entomolosie in d. J. 1886. 



