56 



FOSSIL REPTILIA OF THE 



In the eighth caudal the base of a reduced parapophysis projects from the side of the 

 centrum behind its middle ; a low prezygapophysis projects from the neural arch : but 

 beyond this vertebra all trace of that arch disappears, or is indicated by feeble prominences 

 in the fasciculus of bone-tendons which seem to be attached to neural processes of the 

 non-elongated centrums. Six or seven filamentary bone-tendons, one thicker than the 

 rest, extend lengthwise above the centrum. Some of these may be traced over two 

 centrums, then end in a point, their place being taken by another bone-tendon beginning 

 by a similar pointed end. The parapophysis disappears in the tenth vertebra. 



The caudal vertebrae in the first discovered specimen of Bimoiyhodori'^ answer to the 

 eighth — eleventh in the present series. The elongate centrums of the tenth and succeeding 

 candals, usually more or less uncovered by the bone-tendons, show a low lateral ridge, 

 and a slight expansion at the ends. The hsemapophyses are traceable, much reduced in 

 size, to the fifteenth — sixteenth vertebrae. The bone-tendons are in two fasciculi, one 

 neural, the other haemal, in position. From five to eight may be counted in the side view 

 given of each of these fasciculi. The seeming increase of thickness of some, usually the 

 more peripheral of the filaments, may be due to this flattened form, and to more or less 

 of the side coming into view, instead of the edge. Five or six may be counted in each 

 fascicule, even beyond the twentieth caudal ; the number varying at parts through the 

 formation of the bundle by successive tendons, as above mentioned. They are reduced to 

 two or three at the thirtieth vertebra. The terminal joints of the elongate centrums 

 appear to be flattened and closely adapted, allowing of very little motion. It is evident 

 that, as in BamphorJt.yncJms, the tail was stiff as well as long, and doubtless served as a 

 sustaining ray of the parachute of membrane continued backwards from the wings and 

 hind limbs. 



The vertical diameter of the second caudal showing its neural spine is five lines. 

 The diameter of the ninth vertebra, including the neural and haemal fasciculi of bone- 

 tendons, is the same ; and beyond this the vertebrse and their surroundings gradually 

 diminish to the pointed end of the tail. 



§ Restoration of Dimorphodon. Plate XX. 



The several parts of the skeleton of DimorpJiodon preserved in the slabs of Lias 

 described and referred to in the foregoing pages have ultimately yielded the desired result 

 of their scrutiny and comparison, viz., a restoration of the extinct animal, such as I have 

 endeavoured to exemplify in Plate XX ; and I propose to apply that plate in illustration of 

 a summary of the osteology and dentition of Dimorphodon, comparing therewith the 



1 Buckland, loc. cit., pi. 29, a, a. I have had these vertebvse carefully redrawn, from the specimen, 

 in Pi. XIX, fig. 3. 



