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Show 170 MR. G. A. BOULENGER ON [Feb. 17, nothing to do with the division of the vertebra. I have also noticed a less complete division, or rather bifurcation, of the caudal neural spines in Agama bibronii. The specimen further shows very clearly the paired intercentral hypapophyses at the base of the tail, to which attention was called by m e at a previous meetingl. Returning to the classification of Lydekker, I can only repeat what I have said above as to his division of the Rhynchocephalia into two suborders Homceosauria and Sphenodontina, that the only Fig. 2. Lateral view of middle caudal vertebra?, and lower view of second sacral and three anterior caudal vertebra of Lacerta ocel/ata. Twice natural size. diagnostic differences revealed by the definitions are that in the former the praemaxillaries apparently do not form a beak and the ribs have no uncinate processes, whilst in the latter the praemaxillaries form a more or less deflected beak and the ribs have uncinate processes. These characters, even if well founded, would be insufficient for subordinal separation ; but they are not exact, for it is well known that Sphenodon has praemaxillary teeth; it is therefore 1 See above, p. 114. |