On <i neio Species of l)c\tOi\us from Yorkshire. 410 



K.Xl'IANATION OF rj>ATl': X. Ti-.s. 1, 1//, I />. 



/'/]y. 1. Euphinuii'pK loni/rrvui>, iien. et sp. ii. ; tlie more complete side of 

 tlie fu8.»il and it^^ cuiinterpait (\ n), mit. size, witli scale (1 6) 

 enlaip'd fen times. — I'pper l)iV()iiiiiii ; Scaiimenac Hay, 

 rroviiice of (^Ufbec, Canada, [liiitish Museum.] 



r., caudal tin ; d., dorsal tin ; o., orbits. 



L\ I. — ( hi a new Species of Del tod us Jrom the Lower Car- 

 bon iferous {Yoredale Rocks) of Yorkshire. Jiy A. Smith 

 WooDWARi), LL.D., P^L.S. ■ 



[Plate X. figs. 2, 2 rt, 2 h.] 



The dental plates of some of tlie Palfeozoic Cochliodont 

 sharks attain a considerable size, but those referable to the 

 genus J>i'U<tdus, as defined in the British Museum Catalogue, 

 have not hitherto been remarkable in tliis respect. A new 

 specimen, presented to the British Museum by the Rev. Addi- 

 son Crofton, M.A., is therefore of much interest as showing 

 that at least one species of Deltodas rivalled the largest 

 .'jpecies of some allied genera in size. This fossil was dis- 

 covered by the donor in a dark-coloured limestone of the 

 Yoredale Series on BUickfhorn Farm, between Long Preston 

 and Slaidburn, North Yorkshire. It is shown of three 

 quarters the natural size from the oral and attached faces 

 and from the hinder aspect in PI. X. \^^^s. 2, 2 a, 2 b. 



'i his dental plate is much inrolled at the attenuated outer 

 margin ; it is tiius of the form commonly assumed to belong 

 to the lower jaw. If it be truly lower, it is the hinder dental 

 plate of the left mandibular ramus. Its curvature is not 

 directly at right angles to the long axis of the ramus, but 

 very oblique, so that the antero-lateral margin (a.) is much 

 longer than the postero-lateral margin [p.). Its outer in- 

 rolled j)ortion is obscured by the matrix, but the inner 

 margin (/.) is well preserved and seen to be gently sinuous. 

 Its maximum transverse measurement at the inner margin is 

 0*06 m. The coronal surface is only gently convex and the 

 small hinder wing of the plate is not sharply defined by any 

 depression or flattening. The upper functional portion is 

 crossed by eight or nine rounded and sinuous furrows, be- 

 tween each two of which the crown is slightly raised into a 



27* 



