384 BRITISH FOSSIL REPTILES. 



To which of these large species the teeth and bones next to be described belong is 

 not satisfactorily determinable, but indications of their appertaining to more than one 

 such species now and then occur with more or less significancy. 



Teeth. 



Various teeth, but few quite entire, have been rescued by the care and perseverance 

 of Mr. Lucas Barrett from the rubbish of fragmentary fossils accumulated during the 

 diggings for phosphatic nodules in the Green-sand deposits near Cambridge. Guided 

 by the proportions of length to breadth, by the elliptic section, and the concordance of 

 the minute markings on the crown and base with those on the portions of teeth, as in 

 PL 7, fig. 2, d, and 6, b, remaining in the jaws of Pterodactylus SedgivicJdi, many of 

 the above detached teeth can be satisfactorily referred to the genus, if not to that par- 

 ticular species. 



The base or implanted part of one of the largest of these teeth is figured of the 

 natural size in PI. 7, fig. 10. It has belonged to a Pterodactyle as large as that 

 represented by the fragment of jaw (fig. 6) , if not to the same individual ; it presents 

 the same elliptical transverse section as the implanted base of the tooth in fig. 6,6; 

 shows a widely excavated pulp-cavity at the base, and gradually tapers to the crown ; 

 the cement, about ^d of a line in thickness, is roughened by longitudinal grooves, not 

 continuous for any great length, but uniting, or bifurcating, in an irregular reticulate 

 pattern, forming long and very narrow meshes, the raised interspaces being equal 

 in breadth to the grooves. In a few teeth the base shows an oblique depression, 

 evidently due to the pressure of a successional tooth, as at fig. S, o ; in these the 

 basal pulp-cavity is more or less filled up by ossification of the pulp. The 

 enamel of the crown seems smooth and polished, and, under the lens, shows only 

 extremely delicate, slightly and irregularly wavy, longitudinal, but often interrupted 

 or confluent, ridges. The crown is straight in a few teeth, as at PI. 7, fig. 9, but 

 more commonly it is bent, as it is in the tooth of the great Pterodactyle from the 

 Chalk figured in PI. 3 (Pterosauria), fig. 5. In general, the transverse section of the 

 crown is less truly elliptical than that of the base, owing to its being a little flattened 

 on one side. The smaller teeth, probably from the back part of the dental series, are 

 rather more curved than the larger ones (PI. 9, figs. 16 — 20). 



If, as is most probable, the median ridge of the bony platform between the 

 alveolar borders characterises the upper jaw, and the median groove of the same part 

 the lower jaw, in the Pterodactyle, the parts of Pterodactylus compressirostris, 

 PI. 3, figs. 8, 9, and 10, will belong to the lower jaw. 



