6 THORELL & LINDSTRÖM, SILURIAN SCORPION FROM GOTLAND. 



Scorpion there are impressions of the valves of a Leperditia and also of a few other 

 smaller Ostracoda. 



The remains of this Silurian Scorpion consist only of the thin integument, and 

 it probably is still nearly as chitinous as when imbedded. No fragment could be spared 

 in a specimen of so great value, to ascertain whether its chemical nature had been 

 changed. What Fritsch has said ^) concerning the preservation of the Bohemian fossil 

 Scorpions can literally be applied to our specimen. Since the time Avhen the soft 

 aniraal tissues were removed by pntrefaction — or inay be that this integument is merely 

 the slough left when the animal shed its skin — the specimen has been entombed on 

 the bottom of the Silurian sea, in soft, clayey strata, near the shore of the land, from 

 which it had been washed out. The former existence of a shore close by is clearly 

 proved by the occurrence of a thin bed of »fossib) pebbles, now cemented by calcite 

 into a conglomerate, after having been rounded or flattened through the action of 

 water, just as the limestone pebbles which are formed by the waves to-day not far 

 from this place further down along the shore of the Baltic. 



When the integument was deposited on the bottom of the Silurian sea, it was 

 disjointed in two parts, the tail and three segments of the abdomen being detached 

 from the anterior portion. It was found in June 1884 by a collector of fossils, Avho was 

 not at all aware of the great importance of his lind, or he Avould have used greater 

 care in extracting it from its bed. Unfortunately it became much damaged and it 

 was broken along a line which passes across the hand of the right palpus, the three 

 succeeding pairs of walking limbs and diagonally across the sixth dorsal plate of the 

 abdomen. The greater part of the hand of the left palpus and also the integument of half 

 the sixth abdominal segment, of the whole seventh abdominal segment, of the first and se- 

 cond segments of the tail and of the tip of the sting were then löst. Of these parts, 

 with the exception of the palpus, there are only impressions of their inferior or ventral 

 surface left in the soft, plastic clay, but these are clear enough to show the keels and 

 granulations. It is evident that the dorsal plates of the abdomen, especially the third 

 and the fourth, have been more or less crumpled and rolled up before being imbedded 

 and that some of the ventral plates have been pushed forward so as to be seen along- 

 side the second and third dorsal plates. The greater breadth of the three hindmost 

 abdominal segments is in part due to the circumstance that the edges of the ventral 

 plates project outside the dorsal plates, as seen on the left side of the fifth and sixth 

 segments. Through the enormous pressure of the mäss of the superimposed rocks, the 

 whole integument has been reduced to the thinness of a leaf, and it easily peels off 

 from its matrix, and the dorsal and ventral plates of the abdomen are so thinned out 

 and compressed together that, at the first look, they seem to form but a single plate. 



') Fauna der Steinkohlenformation Bölimeus, in »Die Arbeiten der geologisclien Abtheilung der Landesdurch- 

 forschung von Böhmen». I, p. 12. »Die sämmtliclien Exemplare von Kralup sind zur Papierdiinne zu- 

 sammengedriickt . . . Auf dem granen Schieferthon erscheinen sie als rothbranne Abdriicke der Chitiuschiclite, 

 welche sich beim Trocknen abhebt, und wären nicht alle Exemplare reohtzeitig mit Terdunnter Gnmmi- 

 lösung fixirt worden, wären sie vom Gestein beim leisesten Hanoh verschwunden. — Die microscopisolie 

 Untersuchung bestätigte das, was Coeda bei dem Exemplar von Chomle fand, dass nämlich trotz der 

 Tauseuden von Jahren, welche die ChitinscMchte alt ist, dennooh ihre feine Zellenstrnktur erhalten ist." 



