788 



ARTHROPODA 



PHYLUM VII 



and Proscorpius Whitfield. The former of these comprises three species occiirring in 

 the Upper Silurian (Clunian) of Gotland and Lanarkshire, and tlie latter a Single 

 one froni the Bertie Waterlime of New York. Pocock has suggested that the 

 supposed mesosomatic " sternites " of Palaeophonus are really broadly laminate 

 gill-bearing appendages, as they have been shown to be in Eiirypterus. Similar 

 appendages occiir also in Eohuthus, and it is inferred that respiratory lamellae lay 

 beneatli tlieni as they do in Limulus. Thus, the breathing organs in primitive 

 Scorpions were gills, and the animals are thought to have been aquatic, possibly 

 even marine. But in Carboniferous genera an important change has taken place, 

 in that the covering plates have closed over the lamellae of the gills, leaving only 

 slit-like openings called Stigmata. Breathing in these forms took place by the 

 admission of air through the Stigmata to lung-books. P. nuntius was blind. 



Eoscorpius Meek and Worthen (Fig. 1514) ; Isohuthus Fritsch ; and Cyclophthalmus 

 Corda, are exaraples of Carboniferous Scorpions. Eoscorpius does not differ in any 

 important respect from living forms, and appears to have been quite as liiglily 

 organised. According to Fritsch the order Scorj^ionida attained its acme during the 

 Carboniferous and snbsequently declined. Imperfect remains have been found in the 

 Trias of Warwickshire, and a species of Tityus Koch occurs in Oligocene amber. 



The Order Pedipalpida (Whip-scorpions, etc.) has two-jointed retrovert chelicerae, 

 and six-jointed, retrovert or chelate, raptorial pedipalpi. The first pair of legs is 



Fig. 1514. 

 Eoscorpius carhonarius Meek and Worth. Goal Measiires • 

 Mazon Creek, Illinois. A, Dorsal aspect of sonia, i/i- B, Pecten 

 or " comb, ' enlarged. 



Fig. 1515. 



Geralinura bohemica (Kusta). 

 Goal Measures ; Rakonitz, Bohemia. 

 Vi (after Kusta). 



yery long and modified as tactile organs. Coxae of second pair of legs placed behind 

 those of the pedipalpi, while the small coxae of the first pair are widely separate 

 and situated above and external to the former. Abdomen segmented, movably jointed 

 to the cephalothorax ; last two or three Segments small, annular, either with or with- 

 outa segmented whip. To this order belong Geralinura (Fig. 1515) and Graeophonus 

 Scudder, from the Carboniferous ; Stenarthron Haase, from the Upper Jurassic Litbo- 

 giaplnc Stone of Bavaria ; and Phrynus Latreille, which occurs Tertiarv and Recent. 



found m Southern Italy, Sicily, and Texas. It has no fossil representatives. 



The extmct order Kustarachnida is represented by a Single family, comprising 



