13IIIANG TILL K. PV. VET.-AKAD. IIANDL. BAND 20. AFJ). IV. N:0 10. ( 



sharp median longitndinal keel. It is consideralvly longer 

 Ihan broad and tapers very much in front, where tlie anteriov 

 horder (a) is short. The nearly straight antero-lateral bor- 

 ders are somewhat longer than tbe postero-lateral borders; 

 and tbe latter are peculiar in being sliarply notc^hed b}^ a 

 sudden contraction of the plate (x) so that their hinder half 

 is not a direet continnation of their anterior half bnt merely 

 extends in a parallel line. The trnncated liinder börder of 

 the plate (j)) mnst have been a little longer than the ante- 

 rior horder, bnt it is mnch fractnred and not distinct. The 

 external snrface, where preserved, is conipletely covered with 

 low and irregularly ronnded or ovate tubercles, which ex- 

 hibit a tendency to arrangement in lines radiating from the 

 centre. They clearly extend qnite to the börder of the plate 

 as far l)ack as the pecnliar pair of lateral notohes (.r) al- 

 ready nientioned. The anterior two-thirds of tlie plate mnst 

 thus have overlapped all the snrronnding elements; and it is 

 extremely probable that the postero-lateral margin behiiid 

 tlie notch on eaeh side was also overlapping, not overlapped. 

 A regnlar marginal stain extends to the same width all 

 ronnd the plate. In certain aspects there is some snggestion 

 of a A-s^haped groove for a slime-canal like that on the oor- 

 responding plate of Bothriolepis, the lower extremities reaching 

 the postero-lateral notches; 1)nt this appearance is almost 

 oertainly deceptive. 



A second specimen of tlie median dorsal plate (no. 2) is 

 mnch distorted, bnt again displays all the essential featnres 

 jnst described. Near its left postero-lateral angle it is 

 pierced by a small ronnd hole, which is probably dne to some 

 accident or defect. 



The next portion of armour most easily recognised is 

 the anterior dorso-lateral plate. One imperfect example from 

 the left side, preserved in counterpart (no. 3), is shown in 

 Hg. 12. The convex side of the fossil, which is fignred, 

 displays for the most part only the innermost lamina of 

 the bone; bnt at the hinder and lower margins it exhibits 

 the whole of its snbstance, with the outer ornamented face 

 and a deep groove in the nsnal situation of the sensory 

 canal which traverses it. The plate is remarkable for its 

 great depth in proportion to its length, and for the slightness 

 of the hend along the longitndinal line which marks the edge 



