SUB-CLASS I 



SELACHI1 



49 



Wodnika stria 

 Riechelsdorf, Hesse. 



Fig. 96. 



Miinst. Enlarged. Kupferschiefer ; 



A, Fin-spine. B, Shagreen granules. 



Miinster; Permian (Kupferschiefer of Germany), (Fig. 96). Nemacanthus, 

 Ag. ; Bhaetic and Lower Jurassic. 



(b) Slender, bilaterally - sym- 

 metrical spines, with little or no 

 smooth, inserted portion, and in- 

 ternal cavity only open at the 

 proximal end. Gnathaca athus, 

 Davis; Lower Carboniferous, 

 Armagh, Ireland. Pristacanthus, 

 Ag. ; Bathonian, Oxfordshire and 

 Normandy. 



(c) Bight and left paired spines, 

 most probably connected with fins. 

 Machaeracanthus, Newb. (Fig. 97) ; 



Meter acanthus, 

 Newb. ; Hapla- 

 canthus, Ag. De- 

 vonian ; Europe 

 and North 

 America. Gyro- 

 cant h us, A g. 

 Lower Devonian 



(Canada) to Upper Carboniferous (Europe and North 



America). 



(d) Paired spines, usually with a 

 broad, truncated base, a large internal 

 cavity and the outer face tuberculated. 

 Probably lateral head spines, as in 

 Menaspis among Cochliodontidae. Ora- 

 canthus, Ag. (Platyacanthus, M'Coy; 

 Pnigeacanthus, St. J. and Worth.; Phodt ra- 

 canthus, Davis.) Carboniferous of Europe 

 and North America (spines already 

 observed on either side of head in one 

 example of 0. armigerus, Traquair, from 

 Calciferous Sandstones of Eskdale, 

 Dumfries). Physonemus, M'Coy (Xystra- 

 canthus, Leidy ; Drepanacanthus, Newb.); 

 Erismacanthus, M'Coy; Gampsacanthus, 

 St. J. and Worth. (Fig. 98); Lecra- 

 canthus, St. J. and Worth. ; Dipria- 

 canthus, M'Coy, etc. Lower Carboni- 

 ferous. 



(e) Spines of entirely doubtful posi- 

 tion. Cynopodius, Traquair. Lower 



Missouri (after st."jonn Carboniferous ; Scotland. Euctenius, 



Traquair. Coal Measures ; Scotland, 

 England, and Ohio, U.S.A. Stethacanthus, Newb. Upper Devonian and 

 Lower Carboniferous ; Ohio, Illinois, and Iowa. 



Fig. '.'7. 



Mocha* racanth us major 

 Newberry. Middle De 

 vonian ; Sandusky, Ohio 

 1 -j nat. size (after New 

 1 terry). 



Gampsacanthus typus, 



St. John and Worthen. 

 Carboniferous Lime- 

 stone ; St. Louis, 



VOL. II 



E 



