THE SCOTTISH SILURIAN SCORPION. 305 



admirable state of conservation tliat even tlieir granulation is 

 still apparent. Nevertheless it must be borne in mind that 

 Peach's opinion on this point is in complete agreement with 

 Thorell's regarding the Gotland specimen. 



According to Thorell this specimen exhibits on its right 

 side a portion of a displaced sternal plate^ upon which a 

 distinct stigma is visible. This sternal plate he assigns to 

 the third somite of the mesosoma ; but a glance at his draw- 

 ing shows that the greater part of it lies at the sides of and 

 beneath the tergite of the second, somite, and that at all 

 events a large part of the third sternite is situated on the 

 left-hand side beneath its corresponding tergite. To hold 

 that this third sternite has been fractured and displaced to 

 the extent that Thorell's interpretation demands appears to 

 me to be an opinion based on an improbability. From the 

 position of the fragment that protrudes on the right-hand side, 

 I jndge that it belongs to the second mesosomatic somite — 

 a somite which in all known scorpions bears the pectines but 

 is without stigmata, — and that it is part of its pleural mem- 

 brane. This interpretation, if correct, involves the conclusion 

 that the " spiraculum " described by Thorell is a fortuitous 

 crack in the integument. There is one other point, too, bear- 

 ing indirectl}^ upon the question of the presence or absence of 

 stigmata, in which, without further evidence, I find it im- 

 possible to accept Thorell's decision. The Swedish specimen 

 is broken in two by a transverse fracture, crossing the fourth 

 somite of the mesosoma. The posterior half thus contains 

 the fifth and sixth mesosomatic somites and the metasoma. It 

 is admitted — and there is no reason to doubt — that the ventral 

 surface of the metasoma is exposed. According to Thorell, 

 however, the two mesosomatic somites which go to make up 

 the severed portion of the body lie back uppermost. This 

 supposition implies the belief that the severed portion of 

 the specimen was itself completely divided into two at the 

 junction of the mesosoma and metasoma, that the latter was 

 overturned, and was so accurately fitted into place that perfect 

 continuity between it and the mesosoma was restored. That 



VOL. 44, PART 2. — NEW SERIES. V 



