208 



PTER1CHTHYOMORPHI 



in the Coccosteomorphi, are evidence of wide divergence. On the 

 other hand, the Pterichthyomorphi have much in common with the 



Fio. 181. 



Pteridithys Milleri, Ag. Dorsal (A), ventral (B), and left lateral aspects (C); restored. 

 (After Traquair, from A. S. Woodward, Proc. Geol. Assoc.) n.d.l, anterior dorso-laterali; ag, 

 angular; a.m. d, anterior median dorsal ; a.v.l, anterior ventro-lateral ; c, central; d.a, dorsal 

 anconeal; d.ar, dorsal articular; e.l, extra-lateral; e.m, external marginal; i.m, internal 

 marginal ; I, lateral ; l.occ, lateral occipital ; ?n, median ; m, m, m, m, marginals ; m.occ, median 

 occipital ; m.v, median ventral ; mx, maxilla ; o, ocular ; p.d.l, posterior dorso-lateral ; pm, pre- 

 median ; p.m.d, posterior median dorsal ; ptm, postmedian ; p.v.l, posterior ventro-lateral ; rf, 

 semilunar ; t, terminal; v.a, ventral anconeal ; v.ar, ventral articular. Dotted lines 'indicate 

 the course of lateral-line canals. 



