KONGL. SV. VET. AKADEMIENS HANDL. BAND. 21. N:0 9. 19 



tus, and in a species wliich he has described and figured without naming it''), there is 

 another deep furrow in front of the hinder one, and thus, by these two transverse 

 furrows and a longitudinal deep median groove, the cephalothorax is divided into six 

 »lobes or inounds.» Recent scorpions show faint traces of this anterior transverse fur- 

 row, in the shape of a slight oblique impression on either side; but in Palteophonus 

 it seems to be quite absent. 



Of the dorsal plates of the abdomen, the anterior ones at least are longer in 

 Palasophonus than in modern scorpions. The shape of the last caudal segment of Pa- 

 Iseophonus does not appear to deviate quite so much from the other caudal joints as 

 in the scorpions of the Recent and Carboniferous periods. This is a fact which, like 

 that of the deeper and straighter transverse groove on the hind part of the cephalo- 

 thorax, is of importance, because these characteristics are evidently expressions of a 

 more primordial, less differentiated or specialized organisation. In recent scorpions, in 

 fact, the fusion of the fourth or last thoracic segment with the next preceding is much 

 more intimate than in Palseophonus, and the last segment of the tail is also more 

 elevated, and has assumed a more bladder-lilte shape, from which it has also been 

 named the »vesicle» (poison vesicle). 



If we take into consideration the differences which are observable between 

 Palseophonus and the scorpions of the Carboniferous formation on the one hand, 

 and between Palajophonus and the recent species on the other, we come to the 

 remarkable conclusion, that Palseophonus in some respects, and especially in the 

 shape of its cephalothorax, more resemhles the recent species than those of the Car- 

 boniferous period. From this again it may be concluded that the last mentioned 

 scorpions are not to be regarded as transitional forms between the Silurian scor- 

 pions and the now living species, but that the Carboniferous and the recent scor- 

 pions constitute two parallel or diverging branches, which have issued from the main 

 trunk of the Silurian period. In the Carboniferous scorpions, in fact, the middle of 

 the front margin of the cephalothorax is produced into a short tip or tooth, as in the 

 Chelonethi (the Pseudoscorpions). In recent scorpions, on the other hand, the anterior 

 margin of the cephalothorax is either truncate, without a median tooth, or emargi- 

 nate in the middle — and this is also the case in Palasophonus. At least in the ge- 

 nus Eoscorpius, the cephalothorax is much more inflated than in recent scorpions, in 

 which it is never »raised on each side into swollen cheek-like lobes which occupy the 

 whole breadth at the anterior and antero-lateral margins, which they overhang and 

 entirely hide when the carapace is viewed from above»^). In this feature also Pala;o- 

 phonus differs from the Carboniferous scorpions and agrees with the recent ones. Mo- 

 reover, the two central or dorsal eyes in the Carboniferous species are much lar ger 

 than in other scorpions; they are also situated closer to the anterior margin of the 

 cephalothorax than in the recent forms, and are consequently placed either between 

 or in front of the two rows or groups formed by the lateral eyes. Recent scorpions, 

 again, have their dorsal eyes placed at a more or less considerable distance from the 

 frontal margin and behind the lateral eyes, which like those of Eoscorpius, are situated 



') On some new species of fossil Scorpions, etc, 1. c, p. 404, Pl. XXIII, figs. 11 and Ila. 

 ■^) Peach, 1. c, p. 398 {Eoscoiyius tuber culatus). 



