18 TERRESTRIAL CARBONIFEROUS ARACHNIDA. 



narrow, scarcely at all inflated, about the width of the preceding segment 

 (brachium), and the back of the band is only about half the length of the movable 

 digit ; the digits are straight and in contact when closed, and the immovable is 

 markedly bent, at the tip . 



Type Species. — Eoxcorpius glaber, Peach. 



In the structure of its post-oral appendages this Scorpion is very peculiar. 

 Judging from Peach's figure the chela? differ structurally from those of all known 

 species, living or extinct, especially in the straightness of the fingers, the narrow, 

 nearly parallel-sided, but short hand, and the extreme shortness of the brachium. 

 The possibility of Peach having made a mistake over this last feature in his 

 restoration has influenced my decision to leave it out of the diagnosis It must 

 not, however, on that account be forgotten, as might well be the case seeing that 

 no mention of the peculiarity is to be found in the text. Nor was the author 



Fig. 3. — Arclueocto.ius glaber (Peach) ; copied from Trans. Roy. Soc. E linb., vol. xxx, pi. xxii, fig. 2b, nat. size. — 

 Lower Carboniferous ; Lang-holm. A. Macconochie Collection. 



struck, apparently, by the anomalous structure of the ambulatory limbs, which his 

 drawings show so well. Another interesting feature not referred to is the 

 presence of a single pedal spur on the terminal joint of the legs, a feature in which 

 this Scorpion resembles the genera belonging to the existing family Scorpionidre. 



Archaeoctonus glaber (Peach). Text-figure 3. 



1883. Eoscorpms glaber, B. N. Peach, Trans. Boy. Soc. Edinb., vol. xxx, p. 400, pi. xxii, figs. 2—2 I. 



Integument smooth, without tubercles. Total length probably about 50 mm., 

 carapace 9 mm., last abdominal + first caudal segment 7 mm., movable digit 

 8 mm., back of hand 3 mm., width of hand 4 mm., of brachium 3 mm. 



Based on two specimens, the type from near the Cementstone Group of 

 the Lower Carboniferous, Langholm, Dumfriesshire, the other from the Calci- 

 ferous Sandstone Series at Redhall, near Slateford, Edinburgh. 



