EXPLANATION OF PLATE LXV. 



Pleuracanthus (Diplodus) Imvissimus, Agass. 

 Figure 



1. Lower jaws in natural position ; reduced to half diameter. 



a. Eiglit lower jaw, under surface. Posterior portion of jaw, apparently divided by centres 

 of ossification into a series of plates. 



b.b. Left lower jaw. Outer margin of the two mandibles thickened by the pressure from the 

 other side of the upper jaws. 



c.c. Terminal ossifications forming the snout, and extending between the anterior extremi- 

 ties of the palato-quadrates. 



d. Plate from the left posterior margin of the cranium. 



e.e. Cranial plates, probably located anteriorly to d. 



2. Pectoral fin (natural size). 



3-15. Teeth from various parts of the jaws (natural size). 



Formation and Locality. — 1, 3-15, Low Main Coal Seam, Newsham, Northumberland; 2. Cannel 

 Coal, Tingley. 



Ex coll. — Atthey Collection, Museum, Newcastle-on-Tyne ; James W. Davis, Chevinedge, Halifax. 



