OPHIDTA. 65 



and fro, and variously contorted as it was swept along by the current ; the portion 

 here preserved has been by some external influences obstructed and bent upon itself 

 in its present unnatural curve, as it finally sank in the sediment in that state of 

 decomposition when the ligaments were ready to give way to the strain upon them ; 

 but the tough integuments, which have longer resisted dissolution, have served to 

 retain the partially-dislocated vertebrae together until they became fixed in the 

 matrix in the position in which they are now fossilized. We have in this condition 

 very good evidence of that long and slender form of body which would admit of such 

 an extent of inflection from external pressure in a direction contrary to that which the 

 natural articulations of the vertebrae would allow ; but since in Serpents those articu- 

 lations are so strong, when fresh, as to offer considerable obstacles to any vertical 

 inflection upwards or downwards, we may infer that the body of the Palceophis, of 

 which the example in question formed a part, must have floated long enough to have 

 undergone that degree of internal decomposition, which allowed it easily to yield to 

 external pressure in any direction. 



The characteristically long and comparatively slender spine is well preserved in the 

 vertebrae at ns, fig. 2 ; and the equally characteristic angular production of the 

 hinder border of the neural arch is shown in some other of the vertebras. In many 

 vertebrae the ribs are preserved just in that degree of juxtaposition in which they 

 would remain after yielding to the pressure and movements of the overlying and 

 accumulating sediment upon the integument of the body. Fig. 3 shows a portion of 

 the coil, in which a few of the ribs offer to our view the concave articular surface (pi), 

 which was articulated with the diapophysial tubercle (d) : in fractured portions of the ribs 

 their medullary cavity is shown. The hypapophysis which terminates the thick and 

 low inferior ridge of the vertebrae of the present species offers that small degree of 

 development characteristic of the middle and posterior part of the long abdominal region. 

 In T. XVI, fig. 1 shows this remarkable chain of vertebrae from the right side ; fig. 2 

 the middle portion of the same chain from the left side ; and fig. 3 the under surface 

 of the vertebrae with the juxtaposed ends of the ribs. 



In T. XV, fig. 1 shows a group of the vertebrae of PalceopMs toliapicus, in some of 

 which the long and slender spine (ns) characteristic of the genus is well preserved. 

 In fig. 3 of the same plate, the position and form of the diapophysial tubercle (d, d) are 

 shown. The character of the under surface of the vertebrae is shown in fig. 4, and the 

 angtdar aliform production of the neural arch is shown in fig. 5. 



One of these characteristic examples of the Palceophis toliapicus is preserved in the 

 Hunterian Museum*, the others in that of James S. Bowerbank, Esq., F.R.S. In the 

 Museum of Mr. Saull, F.G.S., a few vertebrae, and a fragment of the skull of probably 

 the same species of Palceophis, likewise from Sheppy, are preserved. 



* This was figured, by the permission of the President and Council of the College, in illustration of my 

 original Memoir on the Genus Palceophis in the Geological Transactions. 



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