OOLITIC DINOSAURS. 



173 



Monograph of the genus, j^ublished in the vohime of the " Pateontographical 

 Society," for the year 1875 (p. 24, Pis. 8 and 9). 



Subsequently I received from a contiguous part of that coast, and, from the 

 character of the contained or adherent matrix, also from a Wealden bed, a larger 

 vertebral centrum of longer proportions. 



As this specimen was characterised by the unusual proportion of unossified 

 tracts of the bony substance, which I infer to have been occupied by gristly matter, 

 I proposed for it the name of GJiondrosteosaurus. 



Of this genus the centrum of a dorsal vertebra is described in vol. i, p. 622, 

 and figured in Dinosauria, PI. 79, affording an instructive subject of comparison 

 with that of PI. 83 of vol. iv. 



Without a vertical diameter of the same dimensions, 7^ inches, the present 

 vertebra has a length of 8^ inches, while that of Ghrondrosteosaurus, from the same 

 part of the vertebral column, is 1 foot, 3 inches in length ; which seems to indicate 

 something more than a specific distinction. The side-pit of the centrum repeats 

 the generic characters shown in Bothriosfondylus suffossus (vol. i, p. 555, Dinosauria, 

 PL 63) ; and the free surface of the centrum, where entire, shows the same 

 smoothness, as in the type specimens. But it is unnecessary to extend the 

 description of the somewhat mutilated centrum, the sulijcct of PL 83, as an almost 

 entire vertebra, with the centrum but slightly mutilated at the borders of the 

 hinder articular concavity, affords the subject of the folding plate, and of the 

 present description. 



The following are dimensions of this vertebra : 



Centrum, length 



„ breadth of fore articular end 



„ ,, of middle 



„ height of ditto 



Height of entire vertebra 

 Breath across diapophysis 

 Height of spine from between pregygapophyses 



The anterior surface of the centrum, c, is moderately convex : the sides are 

 concave lengthwise, excavated by a cavity, c, 5| inches in length, 3 inches in height, 

 with the aperture of a narrow ovate form, 4^ inches long, 2 inches high, at its fore 

 part, contracting to almost a point behind ; situated at the upper half of the side 

 of the centrum. This cavity has a smooth surface, not communicating with or 

 continued into the osseous tissue, and probably having served to lodge an air-cell 

 continued from the lungs in the living Reptile. 



The outer surface of the centrum beneath the pulmonic cavity, is continued by 



