Guide to the Crustacea, Arachnida, Onychophora and Myriopoda exhibited in the Department of Zoology, British Museum (Natural History) .. . der I.—^lESOTHELAE. In the Mesothelae the spinning appendages consist of two Table-casepails of biramous limbs, which are situated far in advance of the ?^° ^^anus, immediately behindthe pulmonary sacs. Theabdomen is distinctly seg-mented, the upper surfacebeing furnished with aseries of eleven tergal plates,and its ventral surface withtwo large plates overlyingthe pulmonary sacs, and anumber of small platesbehind the spinnerets. In the segmentation ofthe b
Guide to the Crustacea, Arachnida, Onychophora and Myriopoda exhibited in the Department of Zoology, British Museum (Natural History) .. . der I.—^lESOTHELAE. In the Mesothelae the spinning appendages consist of two Table-casepails of biramous limbs, which are situated far in advance of the ?^° ^^anus, immediately behindthe pulmonary sacs. Theabdomen is distinctly seg-mented, the upper surfacebeing furnished with aseries of eleven tergal plates,and its ventral surface withtwo large plates overlyingthe pulmonary sacs, and anumber of small platesbehind the spinnerets. In the segmentation ofthe body and in the positionof their spinnerets, theMesothelae differ from allother living spiders, andresemble certain extinct(Carboniferous) types {Pro-tolycosa, etc.). There is buta single family with two genera (Liphistius and Anadiastotlielc), which occur in Burma,Malacca, and Sumati-a. Specimens have been captured in thedepths of limestone caverns in Malacca, and it is possible thatthe apparent rarity of these spiders is due to their restriction toa cave habitat. A specimen of Liphistius (Icsultor is exhibited inTable-ease Fig. dcs/iltor. J4 Guide to Arachuida. Sub-order II.—OPISTHOTHELAE. Table-case ^\\(i spinning appendages in the members of this sub-order aresituated at the posterior end of the abdomen, just in front of theanus. All trace of the tergal plates of the abdomen has been lost,and remnants only of the ventral plates are to be found protectingthe pulmonary sacs. To the Opisthothelae Ijelong all existing spiders (with theexception of Lijjhistms and Anacliastothele), and the majority ofthose found fossilised in the gypsum or amber-beds and lacustrinedeposits of the Miocene and Oligocene periods in Europe andNorth x\merica. Tribp: I.—Mygalomorphae. In the spiders belonging to this group the posterior pair ofbiramous spinning appendages are usually alone retained. Thebasal segment of the first appendage projects forwards, the fangclosing ba
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectcrustacea, bookyear19
