SÜB-CLASS I 



SELACHIl 



49 



Münster ; Permian (Kupferschiefer 

 Ag. ; Rhaetic and Lower Jurassic. 



(b) Slender, bilaterally - sym- 

 metrica! spines, with little or no 

 smooth inserted portion, and in- 

 ternal cavity only open at the 

 proximal end. Gnathacanthus, 

 Davis; Lower Carboniferous, 

 Armagh, Ireland. Pristacanthus, 

 Ag. ; Bathonian, Oxfordshire and 

 Normandy. 



(c) Right and left paired spines, 

 most probably connected with fins. 

 Machaeracanthus, Newb. (Fig. 97) ; 



Heteracanthus, 

 Newb. ; Hapla- 

 canthus, Ag. De- 

 vonian; Eürope 

 and North 

 America. Gyra- 

 canthus, Ag. 

 Lower Devonian 

 (Canada) to Upper 



of Germany), (Fig. 96). Nemacanthus, 



Wodnika striatula, 

 Riecheisdorf, Hesse. 



Fig. SHi. 



Münst. Enlarged. Kupferschiefer ; 

 A, Fin-spine. B, Shagreen granules. 



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. {Flatyacanthus, M'Coy ; 

 Pnigeacanthus, St. J. and Worth. ; Phodera- 

 canihus, 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,'N ewh.) ; 

 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 

 Carboniferous ; Scotland. Eudenius^ 

 Traquair. Coal Measures ; Scotland, 



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



Lower Carboniferous ; Ohio, Illinois, and Iowa. 



^y. 



Ä 



Fig. 97. 



Machacracanthus vmjor 

 Newberry. Middle De 

 vonian ; Sandusky, Ohio, 

 1/2 nat. size (after New 

 berry). 



Gampsacanthus typus, 

 St. John and Worthen. 

 Carboniferous Linie- 

 stone; St. Louis, 

 Missouri (after St. John 

 and Worthen). 



VOL. II 



