Zooloyical Society. 391 



pactness and extreme thinness of the bones of the skull of the genus : 

 the fine longitudhial striiB of the outer surface are more continuous 

 than in the Pt. Cuvieri, in which they seem to be produced by a suc- 

 cession of line vascular orifices produced into grooves. The conspi- 

 cuous vascular orifices are almost all confined to the vicinity of the 

 alveoli in the Pt. compressirostris. This species belongs, more de- 

 cidedly than the Pt. Cuvieri, to the ' longirostral ' section of the Pte- 

 rosauria : whether it had an edentulous prolongation of the fore part 

 of the upper and lower jaw remains to be proved. 



In attempting to form a conception of the total length of the head 

 of the very remarkable species of Pterodactyle represented by the 

 portions of jaw above described, we should be more justified by their 

 form in adopting the proportions of that of the Pt. longirostris than 

 in the case of the Pt. Cuvieri : but allowing that the external nostril 

 may have been of somewhat less extent than in the Pt. longirostris, 

 we may still assign a length of from fourteen to sixteen inches to the 

 skull of the Pterodactyle in question. 



It could not have been anticipated that the first three portions of 

 Pterodactylian skull — almost the only portions that have yet been 

 discovered in the cretaceous formations — should have presented such 

 well-marked distinctive characters, one from the other, as are de- 

 scribed and illustrated in Mr.Bowerbank's Memoirs and in the present 

 communication. Such, nevertheless, are the facts : and, however im- 

 probable it may api)ear, on the doctrine of chances, to those not con- 

 versant with the fixed relations of osteological and dental characters, 

 that the three corresponding parts of three Pterodactyles for the first 

 time discovered, should be appropriated to three distinct species, I 

 have no other alternative, in obedience to the indications of nature, 

 than to adopt such determination *. 



* The same criticism or objection may be oftered to the conclusions in the text, 

 as tlie following one, which was called forth by my determinations of the species 

 oi Bala^nodon ionaA in the red crag. "The specimens exhibited by I'rof. Hens- 

 low were only eleven in numl)er ; so that, without allowing anytiiing for the cir- 

 cumstance of each whale having two tympanic bones, and the probability of some 

 of the above being in 2>airs, we h<ive the first twelve determinable cetaceous bones 

 discovered in the red crag api»ropriated to no less than_;?w species. 1 have no i)re- 

 tensions to call in question the decision of Prof. Owen upon osteological grounds, 

 but I must own that I am disposed, upon the doctrine of chances, to consider it 

 hardly probable that these determinations are accurate." — Searles V. Wood, Feb. 

 16, 1844, London Geol. Journal, p. 35. 'ihe fifth species is a gratuitous addition 

 to the four described by me, the determinate characters of which have been cori- 

 firmcd by numerous additional discoveries. Mr. Wood should have remembered, 

 before he attempted to discredit the determinations from anatomy, and to substi- 

 tute the numerical test, that the second mammalian fossil from the oolite, although 

 a lower jaw, like the first, was of a different species, and that of five subsequently 

 discovered unequivocal mammalian remains from Stonesfield, all arc paits of the 

 lower jaw, whilst two of them demonstrate a third species. Very imjtrobable this 

 to him, on the doctrine of chances; hut only showing, as Sir Charles Lyell has 

 remarked, " the fragmentary manner in which the memorials of an ancient terres- 

 trial fauna are handed down to us." 



