254 MESSRS. HANCOCK AND HOWSE 



lozenge-shaped areas and lateral plates have a strong resem- 

 blance. On the anterior half the dorsal members of the trans- 

 verse plates and rods are somewhat modified. The central 

 lozenge-shaped plates bearing the ridges and the elongated late- 

 ral plates are continued to the occiput unaltered in character, or 

 only slightly changed in form. Below, or towards the ventral 

 margin, the sigmoidal ridges or plates seem to be replaced by a 

 series of seven large thoracic or ventral plates (m), which are 

 arranged along the margin of the body, those of the two sides 

 meeting on the median line, where doubtless they formed a 

 sharp edge. They are three-eighths of an inch long, and about 

 one-eighth of an inch wide. 



They appear to imbricate forwards, and are of an irregular 

 ovate form, with the posterior margin thin and somewhat flat- 

 tened, and the anterior or overlapping margin thickened, 

 grooved, and a little shouldered above. We say appear to im- 

 bricate forwards ; but in the most perfect specimens there are 

 indications that they are really imbricated backwards, the 

 groove of the anterior margin receiving the thin posterior bor- 

 der of the preceding plate ; and the appearance to the contrary 

 seems to be owing to dislocation. Both extremities of the plates 

 are drawn out, the lower one being considerably prolonged, 

 pointed, and directed backwards. The upper extremities are 

 directed upwards and forwards, and are produced into widish 

 columns («) (the ribbon-shaped organ of G-ermar), the two or 

 three anterior of which, increasing in length backwards, termi- 

 nate immediately behind the clavicle. The posterior ones pass 

 upwards, and are united to the outer extremities of the lower 

 lateral plates near the occiput. These columns, which are di- 

 vided by narrow spaces, present a very peculiar appearance. 

 Each of them is composed of numerous narrow, much elongated 

 plates or rods, with pointed extremities, which, overlapping each 

 other considerably, give to the whole a sort of twisted look. 

 They are probably, however, in a disturbed state. About seven 

 of the lower lateral plates next the occiput are in connexion with 

 these columns, which seem to divide into their component parts 

 as they approach them, two or three being thus joined to each 



