. Ixii. PRESIDENT'S ADDRESS. 



fleshy parts preserved. The tail-fin is shown to be very large, 

 resembling that of the shark, only wider. In the early days of 

 palaeontology Sir Richard Owen, with his rare inductive genius, 

 predicted that the tail had a considerable power in compensation 

 for the diminutive hind limbs of "the Ichthyosaurus, requiring an 

 auxiliary power for progression through the sea. Physiologists 

 are modifying their views \\i\\\ regard to the supposed flexibility 

 of the neck of the Plesiosaurus. It is now contended that it was 

 comparatively rigid, but possessed of considerable freedom, both 

 vertical and lateral, at its juncture with the trunk, giving the 

 animal greater facility for Hatching its prey in compensation for 

 its small head and feeble jaws. Plesiosaurus macroceplialus and 

 P. brachycephalus, which had short necks, were furnished 

 with large heads and powerful jaws. It was supposed to frequent 

 the shallow parts of the sea, and to lurk among the sea-weeds. 

 The occipital condyle which attached the head to the neck was not 

 bent downwards as that of the swan or the horse, but in a 

 straight line with the axis of the vertebral column, the cervical 

 vertebra) gradually increasing in size from the head downwards. 

 Those near the distal end have high and clasping apophyses, 

 causing a considerable degree of inflexibility. The powerful hind 

 limbs and size of the pelvic girdle are in striking contrast to the 

 corresponding elements of the Idliyosaurus, which are, as has 

 been said above, small and slender. 



Mr. A. Strahan, F.G.S., has shown in a paper read before 

 the Geological Society this year that there have been at two 

 distinct periods, disturbances on the south coast of Dorset. 

 The earlier movements took place before the deposition of the 

 Upper, but after that of the Lower Cretaceous rocks, and gave 

 rise to the anticlinal of Chaldon in part, of Osmington, 

 and Bioadwey, with their relative synclinals of Upton and 

 Upwey, and, further west, the large faults at Abbotsbury and at 

 Chilcombe belong to this period. The later or Tertiary group, 

 includes the Isle of Puibeck fold, .the Ringstead fold, the Ridge way 

 and Chaldon disturbances, and the Litton Cheney fault. The Isle 



