29 

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



A. DIARTHRI, 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 suhdivided into — 



1 . Bentirostres. Jaws armed with teeth to their ends ; a bony 

 sclerotic ring ; scapula and coracoid not confluent with one an- 

 other * ; a short moveable tail. 



Ex. Pterodactylus proper. 



2. Subulirostres. Jaws with their ends produced into an edentu- 

 lous point, probably sheathed with bone ; no bony sclerotic ; 

 scapula and coracoid confluent ; a long and stiif tail. 



Ex. Pterodactylus {Ramphorhynchus) Gemmingif. 



The extremity of the upper jaw of the Pterodactylus Cuvieri is 

 sufficiently perfect to demonstrate that it had a pair of approximated 

 alveoU close to its termination, and we may therefore refer it to the 

 Dentirostral division. 



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

 ferent proportions of the beak, accompanied by diiferences in the rela- 

 tive 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 longirostris, the 

 first species discovered and made known by Collini in 1 784 ;f , the 

 jaws are of extreme length and tenuity, and the alveoli of the upper 

 jaw do not extend so far back as the nostril. In the Pterodactylus 

 crassirostris, Goldfuss §, on the other hand, the jaws are short, thick, 

 and obtusely terminated, and the alveoli of the upper jaw reach as 

 far back as the middle of the vacuity which intervenes between the 

 nostril and the orbit, and which Goldfuss terms the ' cavitas inter- 

 media.' 



In the solid or imperforate part of the upper jaw anterior to the 

 nostril, i}\e Pterodactylus longirostris has twelve long, subcompressed 

 teeth, followed by a few of smaller size : the same part of the jaw 

 in the Pt. crassirostris has but six teeth, of which the first four are 

 close together at the end of the jaw, and the first three shorter than 

 the rest. The cavitas intermedia in Pt. longirostris is much smaller 

 than the nostril ; in the Pt. crassirostris it is larger than the nostril. 

 Were these two species of dentirostral Pterosauria to be taken, as 

 by the modern Erpetologist they assuredly would, to be types of two 



* The condition of the scapular arch in the Pt. giganteus, Bow., Pt. conirostris 

 mihi, demonstrates the fallacy of this character. 



t Palseontographia, Heft 1, 4to. 1846, p. 19. 



t Acta Academiae Theodoro-Palatinje, V. p. 58, tab. 5. 



§ Beitrage ziir Kenntniss yerschiedener Reptilien der Vorwelt, 4to. 1831, seel, 

 tab. 7, 8, 9. 



