Ornithosaurian Gemis Ornlthocheli-us. 537 



discerned*, Sceley's first decision is tlie correct one, which 

 coincides with Owen's. Moreover, if this be a lower jaw, 

 and the usual proportion of a lower to an upper obtain, the 

 depth of the tip of the muzzle would be so excessive that the 

 supposition becomes highly improbable. 



Group No. 5. 



Beak lanceolate, compressed, pointed, edentulous. 

 Example : — 



Oniitliostoma. R. Oweo, Rep. Cret. Form. (1859), Suppl. i. pi. iv. 

 figs. 4 & 5 ; and II. G. Seeley, Aun. & Mag. Nat. Hist. (4) vol. vii. 

 p. 35, footnote (1871), and elsewhere. 



It will be useful now to review the specimens other than 

 in the Sedgwick Museum included by authors in the genus 

 Ornithocheirus, and allot them to their particular genus, as 

 detailed above. 



Ornithocheirus clavirostris, R. Owen. 

 Rep. Meso. Form. (1874) pt. i. p. 6, pi. i. figs. 1-4. 



Wealden (Hastings Sand), St. Leonard's-on-Sea. 



In regard to this specimen Owen f Avas loth to believe that 

 the " pair of teeth so anomalously located " (above the 

 palate) was due to anything but an accident. Seelev 

 suspected that the bone would prove to be the dentary, but 

 the presence of the palatal ridge determines it to be the 

 premaxillary. Neither Owen nor Seeley apparently con- 

 sidered the great amount of attrition to which each of the 

 specimens had been su])jected. The variation in the section 

 of the teeth appears purely accidental, according to the 

 degree of -wear the bone has undergone. From a careful 

 examination of the type-specimen we are confident that 

 Oriiithocheirus (^Coluborhynchns) clavirostris is a synonym of 

 O. simus and O. ivoodwurdi, that they are all premaxillary 

 bones, and that the position of the teeth, which would indeed 

 be anomalous above the palate, is to be explained very 

 simply : the wearing away of the tip of the snout ha's 

 exposed the l)ases of these teeth, and not the foot of their 

 crowns near the alveoli, as shown by the restoration (PI. XXII. 

 fig. 5). A similar worn condition of the sides of this 

 specimen has displayed the bases of the teeth here also. 

 Thus it becomes in all respects similar to 0. simus 



* R. Owen, Rep. Cret. Form. (Mon. Pal. Soc. 1801), Suppl. iii. (ab i 

 fig. 5. 

 t Id. ibid. (Mon. Ral. Soc. 1874) pt. i. p. 7. 



