On THE STRUCTURE AND CLASSIFICATION OF THE TrEMATASPIDAE. 
33 
Explanation of Plates. 
Plate I. 
Fig. 1. Enlarged view of tke ventral margin of the dorsal shield, sliowing the rounded 
prominence at a, the small processes &, and the larger serrations at g , /г, i and j. 
Fig. 2. Enlarged view of the median dorsal openings, showing de bony framework on the 
floor and sides of the orbits. 
Fig. 3. Section through de margin of the shield, showing the bony trabeculae uniting the 
dorsal and ventral shields. 
Fig. 4. Section through the anterior median opening. 
Fig. 5. Sectiou through the orbits, showing bony trabeculae on the sides of the same. 
Fig. 6. Section through the posterior median portion of the dorsal shield, showing the pro- 
jecting processes on its inner surface, for the the attachment of muscles. 
Fig. 7. Small plate of unknown origin and significance. 
Plate II. 
Fig. 8, 9 and 10. Three views of a wax model of Tremataspis Schmidti. In fig. 8, the oral 
plates on the right, including the triangulär median one, are reproductions of a cast 
in the St. Petersburg Academy. The plates on the left, and the ventral margin of 
the dorsal shield are partly restored. 
ІНФ&-5- 
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