PLATE X. 



Fig. 



1. Eucephalaspis {Cejjhalaspis) Powriei. This most beautiful specimen shows the 



scales and fins in a marvellous state of preservation. The aspect presented is 

 the ventral one, and the body has been twisted so that the marginal series of 

 scales is on the right-hand side as one looks at the figure, whilst the dorsal 

 series is on the left, as also the dorsal fin, the great lateral scales intervening. 

 The form of the head (see also fig. 5, PI. IX) contrasts forcibly with that of 

 C. Li/ellii or C. A(jassizii, whilst the relative proportion of body and head is 

 different from that presented by the specimens of C. Lyellii in Pis. VIII and 

 XI. This specimen is from near Arbroatli, Forfarshire, and is in Mr. Powrie's 

 Collection. 



2. Portion of the head-shield of a Cephalaspid from Forfarshire, showing the 



orbits as seen from below, with indications of blood-vessels passing in from the 

 subjacent parts. 



3. Eiiceplalaspis [Cephalaspis) Paget, two thirds the natural size. 



4. Another specimen, drawn of the natural size. These two specimens have been 



selected, as showing better than others in Mr. Powrie's magnificent series the 

 surface markings and the scales. These scales are not well represented in 

 fig. 3, in which it is not impossible that the ventral aspect is presented. The 

 dorsal fin is well seen in fig. 4. The woodcut, fig. 21, gives a faithful 

 outline of the head, restored from specimens less crushed than these are. Both 

 from the Cephalaspis-bed, Lower Old Red Sandstone, near Reswallie, Forfar, 

 In Mr. Powrie's cabinet. 

 4a, 4i5». Represent magnified bits, showing the surface markings of some of the scales ; 4(5 

 are, perhaps, ventral scales. 



5. Eucephalaspis {Cephalaspis) asper. This specimen is in a grey nodule, the fossil 



itself having a red tinge. The polygona^ arese are very strongly brought out 

 by the great pressure and the infiltration to which the shield has been sub- 

 jected. A piece of the 'rim' of the shield has become detached, as also in 

 the specimen in fig. 3. Mr. Powrie, 

 5a, bf^i. Represent the under and upper surface of two of the scales of the preceding 

 specimen, with some of the characteristic asperities. 



