J. F. BLAKE ON THE ELMMERIDGE CLAY OF ENGLAND. 223 



Appendix B. 

 On New and Critical Species. 

 Gteodds ornatissimtts, n. sp. 



Beautiful vomerine and mandibular bones of Pycnodont fishes 

 have for some time past been obtained from the clayey beds beyond 

 Sandsfoot Castle, near Weymouth, and have been distributed in 

 various collections, though, from the walling-up of the cliff, their 

 supply will now probably cease. The most beautiful are some finely 

 preserved specimens of Gyrodus. 



The vomer has the exterior rows of teeth not much larger than 

 the intermediate rows ; but the central row is the largest — gradually, 

 however, diminishing in size towards the front, where the central 

 teeth are scarcely larger than those of the side rows. The centre 

 teeth are transversely quadrangular ; the inner knob is double, and 

 the two surrounding edges are very uniformly and conspicuously 

 puckered. The intermediate rows have perfectly circular teeth, with 

 the same ornament. The exterior teeth are, again, quadrangular; 

 and the outside of the first ridge of ornament is raised into a pro- 

 jecting knob. 



Their shape and excessive ornament distinguish these from the 

 teeth of G. Cuvieri (Ag.). 



In the mandibles all the four series of teeth are oblique, the two 

 larger rows being thus rhomboid al. The inner row has eight very 

 small teeth ; the intermediate row is in a very deep furrow ; the 

 middle and outside rows have the teeth approximately equal. The 

 ornaments are as in the vomer. 



These bones vary in size from 1 in. to 1 J in. in length. 



Lower Kimmeridge, Weymouth. 



Pycnodus qtjincttncialis, n. sp. 



An incomplete vomer, showing three transversely oval, central 

 teeth, considerably larger than any others. The outside series show 

 in the space between the two extreme central teeth 4 on one side 

 and 3 on the other, being arranged alternately, the outside tooth on 

 the left side opposite the interspace between two teeth on the right. 

 The intermediate rows are arranged quincuncially with the central 

 row, and are longitudinally oval, but rather oblique ; very minute 

 teeth appear between each of the larger in this row. 



Such an arrangement of teeth appears to be quite peculiar, and 

 to prevent the identification of this with any described species. 



Lower Kimmeridge, Weymouth. 



Ammonites ctmodoce (D'Orb.). 



This species, when old, sometimes loses all its ribs and becomes 

 quite smooth, according to D'Orbigny. I therefore refer such a 

 smooth form to it. 



A. eumeltjs (D'Orb.). 



This may be the same as Mr. Judd's A. marantianus ? 



