MEASURES OF THE TYNE VALLEY 519 



case if it were merely an impression showing through the 

 dorsal plates ; and its centre is in the form, not of a raised 

 plate but of a sunken pit, as would be natural on the inner 

 side of the integument. 



The appendages are a striking feature of the specimen. 

 Unfortunately most of them are tilted in such a way that they 

 present only their edges to the surface. In the nodule as it 

 split originally nothing at all was showing of the legs but these 

 edges ; in the case of the first three legs on the left side it has 

 been possible, however, to chip away the matrix sufficiently to 

 give some idea of what the joints actually preserved are like. 

 The removal of the matrix has left these joints lying in little 

 pits, which for the sake of clearness are not represented in the 

 drawings. No clearing of the appendages has been attempted 

 on the right side ; from the position of the parts and the nature 

 of the matrix it would probably not be successful. 



As to the two first pairs of appendages nothing definite can 

 be stated. The whole carapace is surrounded by an irregular 

 mass of darkish matter, parts of which in certain lights look 

 as though they might be the crushed remains of appendages. 

 Projecting forward from this mass to the left of the middle 

 line in front is a much more definite structure which is very 

 probably part of the pedipalp of that side. Its actual appear- 

 ance is represented in fig. 2. It is slender, about one-fifth the 

 length of the animal, and terminates in what looks like a 

 biramose portion pointing outwards. The forked appearance 

 of this distal piece is probably an accidental effect, due to a 

 longitudinal groove in the joint; the proximal part of the 

 appendage was probably at least as broad as this joint. 

 There is nothing that can be identified in any way as the 

 remains either of the other pedipalp or of the cheliceras. The 

 dark elongated object pointing forward in front of the fossil 

 has, I believe, no connexion at all with it. It shows no 

 arthropod structure, and on the other hand it resembles 

 exactly the little blades of vegetable matter that often occur 

 abundantly in these nodules at Crawcrook. 



