468 H. G. SEELET ON A PTJRBECK ORNITnOSATJRTAN. 



ends so as to be concave in length. The upper surface of the 

 neural arch is limited anteriorly by a slight angle, which is pro- 

 longed backward ; for the two sides slightly converge in passing 

 backward from the outer margin of the prsezygapophyses. 



The praezygapophysis (a) is preserved on the left side only ; the 

 process is about f inch long, it is narrow and carries a narrow zyga- 

 pophysial facet, which looks inward and upward and very slightly 

 forward. The anterior part of the neural arch between the zygapo- 

 physes is not developed so far forward as to quite cover the centrum. 

 The transverse width across the zygapophyses was rather more than 

 ■| inch. In the median line the neural arch is 3J inches long ; it is 

 constricted, and in the middle the width is reduced to -^ of an inch. 

 The posterior end of the neural arch widens to fully -| of an inch, and 

 is natter and more expanded horizontally than the anterior end. It 

 terminates -| inch from the end of the centrum. The posterior 

 zygapophysial facets are not preserved. The lateral outline of the 

 bone above and behind the zygapophysis terminates in a prominent 

 tubercle. 



The centrum appears to be about f inch wide in front, and to be 

 a little wider behind. In front the articular surface («) seems to be 

 concave from side to side, and was evidently shallow, as in the 

 vertebrae from the Cambridge Upper Greensand. The posterior 

 articulation (d) is not convex as in OmithocJieirus, but appears to be 

 nearly flat, though the crushed condition renders its exact structure 

 uncertain. As in vertebrae of OmithocJieirus from the Cambridge 

 Upper Greensand, hitherto regarded as caudal, the pneumatic fora- 

 men is reduced to a small puncture, longitudinally ovate in form, 

 less than -i- inch long; it enters the bone from the front about the 

 middle of the side, and looks more like the nutritive canal of the 

 bone than a pneumatic foramen. 



The largest reputed caudal vertebra hitherto found in the Cambridge 

 Upper Greensand is 1| inch long, and relatively larger at the ends 

 than this, which measures 5 inches in length. 



When the cervical vertebrae of Pterodactylus longirostris are en- 

 larged G diameters, they so closely resemble this type that I greatly 

 doubt the propriety of continuing to regard this vertebra as caudal. 



A detailed comparison with other genera and species may be 

 reserved till other materials occur. I propose to change the specific 

 name, because I have ceased to feel sure that the species had a tail ; 

 aud until the species proves distinct, it may be incorporated with Prof. 

 Owen's Pterodactylus validus, which is founded upon an isolated pha- 

 lange of the wing-finger. 



I offer my thanks to Prof. Hughes for his kindness in lending me 

 these specimens and permitting them to be figured. 



