SUB-CLASS I 



SELACHIl 



49 



Wodiiilca striahUa, 

 Riechelsdorf, Hesse. 





Mlinst. Enlarged. Knpferschiefer ; 

 A, Fin-spine. B, Shagreen granules. 



Minister; Permian (Knpferschiefer of Germany), (Fig. 96). Nemacanth'us, 

 Ag. ; Rhaetic and Lower Jurassic. 



(5) Slender, bilaterally - sym- 

 metrical spines, Avitli 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 ; Europe 



and North 



America. Gyra- 



c a n t h u s, 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 

 Menasjois among Cochliodontidae. Ora- 

 canthus, Ag. [Platyacantlms, M'Coy ; 

 Pnigeacantlms, St. J. and Worth.; PJiodera- 

 cantJms, Davis.) Carboniferous of Europe 

 and North America (spines already 

 observed on either side of head in one 

 example of 0. annigerus, Traquair, from 

 Calciferous Sandstones of Eskdale, 

 Dumfries). Physonemus, M'Coy (Xystra- 

 ccmthiLS, Leidy ; Drepanacantlms, Newb.) ; 

 Erismacanthus, M'Coy ; GampsacantJms, 

 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, 



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

 Ohio, Illinois, and Iowa. 



Maduteraeanthus major, 

 IN'ewberry. Middle De- 

 \'onian ; Sandusky, Ohio. 

 Va nat. size (after New- 

 berry). 



Gampsacanthus typus, 

 St. John and Worthen. 

 Carboniferous Lime- 

 stone; St. Louis, 

 Missouri (after St. John 

 and Worthen). 



England, and Ohio, 

 Lower Carboniferous 



VOL. II 



