520 AN ARACHNID FROM THE COAL 



Portions of all the four legs are seen on each side. But as 

 already explained, it is only on the left that it has been found 

 possible to expose them with any degree of completeness ; 

 indeed even on that side it is only two limbs (one joint in 

 each) that give much idea of their true form. It is clearly the 

 same joint that is showing in each leg, and this joint I take to 

 be the femur. The coxse do not appear to have projected 

 beyond the carapace ; and between them and the joints ex- 

 posed there are in several cases knotty masses which might 

 conceivably be remains of the trochanters. The outstanding 

 characteristic of these joints, whether femora or not, is their 

 extraordinary breadth — more than a third of that of the 

 carapace. In the specimen itself they give the impression of 

 being essentially a normal joint (like the femur of Aiithraco- 

 siro, fig. 5) plus a flattened forward expansion. The hinder 

 border, corresponding to the normal joint, is much thicker 

 than the expanded part, and forms a raised ridge at the back 

 of it. It is itself marked by longitudinal ridges, and these in 

 the second leg are distinctly granulated. The femur of the 

 first leg shows what is apparently its proximal end ; it is 

 narrowed towards that end and appears to be somewhat 

 squared off at the articulation. The corresponding part of 

 the second femur is very imperfectly preserved, but traces of a 

 similar structure can be made out in certain lights. The 

 removal of the matrix at the front of the second femur has 

 revealed something suggestive of one or two succeeding joints 

 folded forward beneath the femur (compare fig. 5); but this 

 is much too indistinct to admit of any definite statement. 

 The femora of the remaining legs are tilted forwards and 

 downwards at so steep an angle that it is hardly possible to 

 follow them down into the matrix. The little that is seen of 

 them, however, suggests that they were much like those that 

 are exposed ; on nearly all of them can be seen traces of the 

 ridges about the hind border. Their forwardly tilted position 

 is possibly that of life; it is difficult at any rate to see how 

 the legs could have been used if these broad, flat femora had 

 all been held horizontally. On the left side, and apparently 



