ARTHROPODA 



PHYLUM VII 



and Proscorpius Whitfield. The former of these comj)rises three species occurring in 

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

 one from the Bertie Waterlime of New Yoi'k. Pocock has suggested that the 

 supposed mesosomatic " sternites " of PalaeopJbonas are really broadly laminate 

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

 appendages occur also in Eobuthns, and it is inferred that respiratory lamellae lay 

 beneath them as they do in Limulus. Thus, the In-eathing 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 jjlates 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) ; Isobuthus Fritsch ; and Cyclophthahnus 

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

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

 organised. According to Fritsch the order Scorjiionida attained its acme during the 

 Carboniferous and subsequently 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 Wortli. Coal Measures ; 

 Mazou Creek, Illinois. A, Dorsal aspect of soma, Vi- -B, Pecten 

 or "comb," enlar.ned. 



«S^^ Fio. lol5. 



Ge/rallnura hohemica (Kusta). 

 Coal Measures ; Rakonitz, Bohemia, 

 i/i (after Kusta). 



very 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 tlie former. Abdomen segmented, movably jointed 

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

 out a segmented whip. To this order belong Geralinura (Fig. 1515) and GraeopJionus 

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

 graphic Stone of Bavaria ; and Phrynus Latreille, which occurs Tertiary and Recent. 



The order Palpigradi is constituted by the single Recent genus Koenenia Grassi, 

 found in southern Italy, Sicily, and Texas. It has no fossil representatives. 



The extinct order Kustarachnida is represented by a single family, comprising 



