ENCHODUS. 



59 



that when seen from the outer face, as in the specimens figured, radiating rows of 

 minute teeth can be observed on its inner or oral face. This plate is elongate- 

 triangular in shape, deepest behind and tapering in front. The ectopterygoid 

 (fig. 2, ecpf.) is a stouter, long and narrow lamina, in a plane sloping downwards and 

 outwards to its somewhat thickened lower border. It tapers at both ends and its 

 deepest portion is just behind the palatine element, which it underlaps. A fragment 

 of its anterior end with part of the overlapping palatine is shown, upside down, from 

 the inner face, by Agassiz, loc. cit., pi. xxv c, fig. 6, and is re-drawn in PL XIV, 

 fig. 3. The complete bone bears a single series of five or six; widely-spaced teeth, 

 which are lanceolate, much laterally compressed and sharply pointed, with the 



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Fig. 13. Enchodvs Icwcsirtmia (Mantoll); diagram of jaws, left side, outer aspect. English. Chalk, d., dentary; 

 ecpt., ectopterygoid (somewhat in perspective) ; mi., maxilla; pi., palatine ■ pmx., premaxilla. 



anterior and posterior edges acute, and the lateral faces marked by delicate longi- 

 tudinal striae. These teeth are scarcely recurved, but their anterior t'(\u;c exhibits 

 a slightly sigmoidal flexure, while their posterior edge is straighter. Their spacing, 

 like that of the mandibular teeth, varies in different individuals; for each succes- 

 sional tooth arises either in front of or behind the corresponding functional tooth, as 

 already described in Cimolichthys (p. 46). Again, as in the mandible, there is some 

 variation in the relative size of the teeth, even on the two sides of the same jaw. 

 The foremost tooth (fig. 3, a.), on the extension beneath the palatine, is of moderate 

 size, while the second tooth (b.) is the largest of the series. The three or four posterior 

 teeth, shown by Agassiz, loc. cit., in his figs. 1, 2, rapidly decrease in size back- 

 wards. The palatine (fig. 2, pi., figs. 4 — 6) is a remarkably thick and tumid bone, 

 quite smooth, and hearing only a single large tooth at its anterior end. It occupies 



