MEASURES OF THE TYNE VALLEY 513 



are as follows. Though the cephalothorax is convex, clear 

 imprints of the coxae are bulged up through it on one side. 

 The anal ring is too sharply marked to be a mere impression 

 showing through the integument. The abdominal plates are 

 undivided, the transverse median pieces not being separated 

 by sutures from the oblique side-pieces as they are on the 

 dorsal side of Auihracosifo and other Anthracomarti. And 

 further, in cases where the ventral details are showing through 

 the dorsal plates they are mixed with details of the dorsal 

 surface, none of which can be recognized here. My chief 

 reason, on the other hand, for supposing that we are looking 

 upon the inner surface of the ventral integument is that the 

 body is distinctly overlying the legs. In the cephalothorax, 

 too, there is a border of integument enclosing the impressions 

 of the coxae outside and pretty plainly overlying them. And 

 there are various points, especially the relief of the borders of 

 the abdominal plates, w^hich tend to show that it is the inner 

 surface that is exposed rather than a negative impression or 

 natural cast of the outer surface. 



In size and general shape the Crawcrook specimen agrees 

 fairly closely with Anthracosiro woodwardi Pocock, and may 

 possibly be a further example — the third — of that species. 

 The other two were found in clay-ironstone nodules near 

 Dudley in the Staffordshire coal field, and are now in the 

 British Museum. They have been fully described by Pocock*. 

 The present specimen differs so much from them in details of 

 aspect and exposure, however, that it is impossible to describe 

 it merely by comparative references to Pocock's account and 

 figures. It is therefore described below part by part. 



The cephalothorax is a good deal crushed. It is strongly 

 convext. The precise outline cannot be traced with perfect 

 certainty all round ; it appears to be roughly semicircular but 

 somewhat angulated in front, nearly parallel-sided or sHghtly 



* R. I. Pocock, Geol. Mag., 1903, pp. 247, 405. 



t See remarks on distortion of abdomen, p. 515, for a possible explanation of the 

 convexity of the cephalothorax. 



