EXPLANATION OF THE PLATES. 
* PLATE 39. 
Vitreous sand-tubes found at Drigg in Cumberland. 
Fig. 1. represents a portion much contorted, of the natural size. 
Fig. 2. is a small ramification. 
Fig. 3. exhibits the lower part where it struck a granite pebble. 
Fig. 4. represents a portion of the thickest part of these tubes drawn to the 
full size. 
Fig. 5. a portion that is forked. 
Fig. 6, 7, 8, 9. Sections of various parts of the tubes, taken across. 
' PLATE 40. 
Osteology of the head of the Ichthyosaurus. 
Fig. 1 to 8. Transverse sections of the left lower jaw, shewing its composition ; 
figures 1 and 3, also take in the upper jaws. 
Fig. 9. Side view of the head. 
Fig. 10. Lower jaws seen from beneath. 
Fig. 11. Head seen from above. 
Fig. 12. Roof of the mouth. 
" PLATE 41. 
Fig. 1 to 11. Vertebrae of the Plesiosaurus. 
Fig. 12 & 13. Vertebrae of the Ichthyosaurus. 
' PLATE 42. 
Fig. 1 Sc 2. Fragments of the paddle of the Plesiosaurus. 
Fig. 3. Scapula, coracoid bones, humerus, radius and ulna, of the Plesio- 
saurus. 
Fig. 4. Humerus, radius and ulna, seen in another point of view, with the 
carpal bones attached. 
Fig. 5. The whole paddle conjecturally restored. 
Fig. Q. One of the ribs. 
All the figures, except 5, are half the size of the original. 
