THE REGION OE THE SPINAL CORD 



415 



rather a free pleuron, which has been easily pushed at an angle to 

 the body-skeleton in the process of fossilization. Patten thinks that 

 this fringed appearance is evidence of a number of segmental appen- 

 dages which were jointed to the corresponding body-segments, and in 

 the best specimen at the South Kensington Natural History Museum 

 he thinks such joints are clearly visible. He concludes, therefore, 



B 



Fig. 161.— A, Facsimile of Woodward's Drawing of a Specimen of Cephalaspis 

 Murchisoni, as seen from the side. The Cephalic Shield is on the 

 Right and Caudal to it the Pleural Fringes are well shown ; B, 

 Another Specimen of Cephalaspis Murchisoni taken from the same block 

 of Stone, showing the Dermoseptal Skeleton and in one place the 

 Pleural Fringes, be. 



that the cephalaspids were arthropods, and not vertebrates. I have 

 also carefully examined this specimen, and do not consider that what 

 is seen resembles the joint of an arthropod appendage ; the appear- 

 ance is rather such as would be produced if the line of attachment of 

 Patten's appendages to the body were the place where the pleural 

 body folds became free from the body, and so with any pressure a 



