LIASSIC FORMATIONS. 



1-7 



the sacrum and contiguous vertebra3 is figured in PI. XIX, fig. '2 ; and the constituent 

 bones are rightly recognised by Buckland (op. cit., p. 222). 



It is interesting to note, that the pelvis of Fleromuria, so determined, reseml)lcs more 

 closely that of the existing representatives of the section of Bcplilia with the 4-chambered 

 heart and double-jointed ribs, viz., Crocodilia, than it does the pelvis in Chelonia and 

 Lacertia. The ischium in Crocodilia, e. g., surpasses the pubis in size, and excludes that 

 hajmapophysis from the acetabulum.^ The ischium seems to contril)ute the larger share 

 of the acetabulum in Dimorphodon, PI. XVIII, a- In Birds, as in Lizards, the puliis 

 forms part of the acetabular cavity .- 



In the specimen, PI. XVIII, a portion, cd, of a long tail, of which the vertel)r3c were 

 surrounded by numerous slender bone-tendons, extends backward and downward beyond 

 the j)elvis : a better preserved portion with three caudal vertebrae (c d') is preserved in a 

 detached part of the matrix found in the vicinity of the larger slab. But to this part of 

 the vertebral column I shall return in describing the more perfect specimen of the tail of 

 Dimorphodon, from another individual (PI. XIX, fig. 4). 



Behind the skull are four cervical vertebrae (PI. XVIII, c), and part of a fifth in natural 

 juxtaposition, or perhaps a little separated at the articular surfaces. The under surface of 

 the centrums and articular processes of the neural arches are exposed. The sides of the 

 centrums show a slight concavity, but their crushed state obscures the natural contour of 

 the under surface. The hind part of the under surface, in the last two of these 

 vertebra), shows a pair of low obtuse processes, with an indication of a convex terminal 

 articular surface. The centrum expands in breadth as it advances, and sends out a short 

 thick process (parapophysis) from each side of the fore part ; to which, in the last three 

 vertebrae, are indications of attachment, or parts, of a backwardly produced styliform rib. 

 At the midline of the fore part of the last two of these vertebrae a fracture indicates a 

 ridge or process there to have been broken off. The pre-zygapophyses are thick, and project 

 far in advance of the concave anterior articular surface of the centrum : the convex 

 posterior articular surface of the centrum projects as far beyond the post-zygapophyses. 

 Their joints are more vertical than horizontal : the posterior surfaces looking slightly 

 outward and downward. 



The superior breadth of the neural arch, as compared with that of the centrum, 

 brings its articular processes into view, along each side of the vertebral bodies, in the 

 degree shown in PI. XVIII, c. The character of the articulations indicate less extent and 

 freedom of movement of the cervical vertebrae than in Birds, and more restriction in the 

 lateral than in the vertical directions. The interlocking joints resulting from the diflfcrent 

 lengths of the fore and hind articular processes add strength to the part of the spine 

 supporting the head. 



The cervical vertebra; of Dimorphodon, so far as their structure is exemplified in the 



1 'Anatomy of Vertebrates,' vol. v, p. l!s8, fig. 119. 



2 lb., p. 190. 



