268 EXPLANATION OF PLATES. 



EXPLANATION OF PLATES IX., X. 



The following letters apply to all the figures of Dorypterus Hoffmanni. 



a, dorsal fin ; a\ narrow posterior prolongation of ditto ; a", anterior 

 prolongation, or fin-fulcra of ditto ; b, anal fin ; b\ posterior, narrow pro- 

 longation of ditto ; c, pectoral fins ; c', brachial rays ; d, ventral fins ; e, 

 rhombiform scales of the tail ; /, fin-fulcra of ditto ; g, lateral plates or 

 vertebral spines ; g\ bifurcation of the inner extremity of ditto ; h, lozenge- 

 shaped plates, or areas, — the vertebral centres ; h\ ridge in the centre of 

 ditto; i, rods, or supplementary vertebral spines, in connexion with the 

 lateral plates ; j, sigmoidal ridges ;f, sigmoidal plates ;_;'", ridge or mucus- 

 tube in the centre of ditto ; k, hour-glass-shaped plates or fin-supports ; I, 

 large ditto at the base of the dorsal and anal fins ; m, ventral or thoracic 

 plates ; n, compound columns in connexion with ditto ; o, great abdominal 

 rods ; p, mandibles ; q, prasmaxilla ; q\ maxilla ; r, clavicle; s, operculum ; 

 t, prseoperculum ; u, orbit ; v, fragments of dark granular matter, appa- 

 rently dermal. 



PLATE IX. 



Fig. 1. General view of the restored skeleton of Dorypterus Hoffmanni. 



Fig. 2. Much enlarged view of three of the transverse rods and plates. 



Fig. 3. Much enlarged view of two of the plates and rods on the shoulder. 



Fig. 4. Portion of two rays of the dorsal fin, showing the joints. 



PLATE X. 



Fig. 1. Specimen of Dorypterus Hoffmanni, exhibiting the head, ventral 

 plates, and ventral fin in good order. 



Fig. 2. Another specimen, exhibiting the tail, pectoral fins, base of dorsal 

 fin, gill-covers, ventral plates, the skin, and the various plates 

 and rods. 



Fig. 3. Specimen of Dorypterus Hoffmanni, exhibiting the dorsal fin, pec- 

 toral fins, and lateral plates with the lozenge-shaped areas and 

 central ridges. 



Fig. 4. Specimen of Dorypterus Hoffmanni, exhibiting the dermal plates 

 with the lozenge-shaped areas and ridges, particularly the plates 

 on the shoulder with the upper line of ridges or mucus-tubes. 



