CRETACEOUS FORMATIONS. 37 



As, however, I have no personal feeling with regard to mere names, I shall 

 apply to the specimens of the jaws of the Pterodactyles, described in this Monograph, 

 the names by which Mr. Bowerbank first made those parts known to Geologists, 

 and before entering upon their descriptions shall premise a few remarks on the 

 Pterodactyles in general. 



The Order Pterosauria includes species of flying reptiles, so modified in regard to 

 the structure and proportions of the skull, the disposition of the teeth, and the deve- 

 lopment of the tail, as to be referable, even according to the partial knowledge we 

 now possess of this once extensive group, to different genera. 



M. von Meyer, e. g., primarily divides the Order into : — 



A. Diarihri. With a two-jointed wing-finger. 



Ex. Pterodactylus ( Ornithopterus) Lavateri. 



B. Tetrarthri. With a four-jointed wing-finger. 



Ex. All the other known species of the Order. 



These again are subdivided into : — 



1. Dentirostres. Jaws armed with teeth to their ends: a bony sclerotic ring: 



scapula and coracoid not confluent with one another :* a 

 short moveable tail. 

 Ex. Pterodactylus proper. 



2. Subulirostres. Jaws with their ends produced into an edentulous point, pro- 



bably sheathed with horn : no bony sclerotic : scapula and 

 coracoid confluent : a long and stiff tail. 



Ex. Pterodactylus {Pamjphorhynclms) Gemmingi.f 



The extremity of the upper jaw of the Pterodactylus Cuvieri, Bowerbank, is 

 sufficiently perfect to demonstrate that it had a pair of approximated alveoli close to 

 its termination, and we may, therefore, refer it to the Dentirostral division. 



In this division, however, there are species which present such different propor- 

 tions of the beak, accompanied by differences in the relative extent of the dental 

 series, as would, without doubt, lead to their allocation in distinct genera, were they 

 the living or recent subjects of the modern Erpetologist. In the Pterodactylus 

 lonyirostris, the first species discovered, and made known by Coliini in 1784,1 the jaws 

 are of extreme length and tenuity, and the alveoli of the upper jaw do not extend so 



* The condition of the scapular arch in the P. giyanieus, Bow, P. conirostris, Mihi, dtnioustrates 

 the fallacy of this character. 



f Palseontographica, Heft I, 4to, 1846, p. 19. 



% Acta Academise Theodoro-Palatinae, v, p. 5S, Tab. v. 



