KKV-TAIJIJ-;. 121 



3. Nodular plates with an excavate margin met with in the following species : 



A. A\'ith flattened base, from 7 — 9 mm. in diameter, S. coronal ui^, PI. XXIV, 



fig. 2. 

 „ „ ,, o — I- mill. ,, S. squamfitui^yVl.XW, 



fig. 3. 

 r. AVilli produced base, )S'. pistilllferHn, PI. XXV, fig. 5. 



4. Oblong or almost oblong plates having the characteristic ornament of ti. 

 hitlbifents. These are the more distal marginals, or in some cases the ventro- 

 lateralia of this species. Generally the marginals are indented at the corners, and 

 their shape can be decided fi'om the characteristic breast-plate form. 



Text-fig. 4, p. 113. — Outer view of plate. 

 Text-fig. 31. — Side view of plate. 



Text-pig. 31. 



5. Irreo'ularlj rounded or polygonal i)lates with occllate depressions having a 



raised ridge. 



A. Without madreporiform markings on summit. S. argus. PI. XXIX, 



fig. 8 a. 



B. With madreporiform markings on summit. S. ocellalus. Text- 



fig. 32. 



Tbxt-fio. 32. 



6. One specimen of Astroprctrn? sp. and LiucLin. sp. ? respectively have also 

 been described, see pp. 90 and 100. 



Urrr.ii Gkeensand Foums. 



The genus Comptonia appears to be characteristic of this horizon. Tlie plates 

 are very similar in shape to those of Cullulcruut, except that tlicy are more 

 rounded in profile. Unfoi-tunately, no specimen at present known shows the 

 ornament of the marginalia. 



