ORDER GANOIDEI. 



9^3 



Dr Traquair considers that this appendage was probably present. 

 Some of the species attained very large dimensions. 



Fig. 892. — Reduced restoration of the dorsal (1) and ventral (2) aspects of Pterichthys comutus, 

 with the sculpture omitted; from the Devonian of Scotland. The thin black lines indicate the 

 concealed edges of the overlapped plates, and the double dotted lines the grooves of the lateral 

 line system, m.occ, Median occipital plate; l.occ, Lateral do. ; ag, Angular plate; pt.nz, Post- 

 median do. ; p. in, Premedian do. ; /, Lateral do. ; e.l, Extra-lateral do. ; Jim, Mental do. : s.l, 

 Semilunar do. ; a.7n.d, Anterior median dorsal do. ; p.m.d, Posterior do. do. ; a.d.l, Anterior 

 dorso-lateral do. ; p.d.l, Posterior do. do. ; a.v.l, Anterior ventro-lateral do. ; p.v.l, Posterior do. 

 do. ; m.v, Median ventral do. ; ar, Articular plate of limb ; a, Anconcal of do. ; c, Central of do. ; 

 m, Marginal of do. (After Traquair.) 



Microbrachius, of the Scottish Devonian, is an allied form distin- 

 guished by the smaller size of the pectoral limb ; in this form also 



*M: JP 



Fig. 893. — Reduced left lateral aspect of Pterichthys comutus ; from the Devonian of 

 Scotland. Letters as in the preceding figure. (After Traquair.) 



no caudal scales have been observed. The length of the head and 

 carapace in the one known species is one and a quarter inches. 



