LIASSIC FORMATIONS. 
63 
of similar size. Even in Bhamphorhj/nchus Gemmingi the cranial convexity is not posterior, but 
is limited to the temporal fossae behind the orbit, as in the specimen figured by Von Meyer 
in pi. ix, op. cit. ; and this indication of the optic lobes is less conspicuous in the subject of 
pi. X, fig. 1. In BimorpJiodon there is still less trace of this alleged Avian characteristic. 
The bone which, in the Bird, as in the Pterosaur, forms part of the otocrane, articulates 
with the ex- and par-occipitals behind, with the alisphenoid in front, with the parietal above, 
and with the petrosal within, which contributes the articular surface to the tympanic and 
the upper rim to the meatus auditorius, also articulates in the Pterosaur, as in the Crocodile, 
with the postfrontal : and this character appears to be constant in the Pterosauria as in the 
Crocodilia, while it is exceptional in Aves. , In the particulars in which the bone 8 differs 
in the Pteroscmrian from that in the Bird, it agrees with 8 in Crocodilia ; as e.g. in its high 
position in the cranium, owing to the low development of the cranial chamber; its 
greater degree of projection from the true cranial walls ; the extensive and suturally fixed 
character of its articulation with the tympanic as compared with the more definite and 
restricted glenoidal movable articulation which the mastoid (8) affords to 28 in Birds. In 
all these circumstances, whether the bone 8 (PI. XX, fig. 1) be called mastoid or squamosal, 
it is Reptilian, not Avian, in the Pterosaur. 
Herr Von Meyer states, in another of his comparisons, that in the Monitor, Iguana, and 
Stellio, the prefrontal (‘ Vorderstirnbein ’) enters into the formation of the periphery of the 
external nostril (Nasenloch).^ This is the case with Varanusf' not with true Monitors.® 
In Tejus nigropunctatus some extent of the suture between the nasal and the maxillary 
intervenes between the prefrontal and the nostril. The non-extension of the prefrontal to 
the external nostril shows no Avian affinity in Pterosauria ; rather an agreement with the 
majority of Reptilia, as, for example, with the whole order of Crocodilia. 
In some Crocodilia {Teleosaurus) and Lacertilia [Chlamgdosaurus, Lgrioceplialus) 
there is an antorbital vacuity, which, in the latter Lizard (PI. XX, fig. 3, a), is equal in size 
with the nostril (ib., n) and intermediate in position between that cavity and the orbit (ib., o), 
which is large. A process of the maxillary rises obliquely backward to join the nasal, and 
to separate the intermediate vacuity from the external nostril. The lacrymal and pre- 
frontal form the bar dividing the intermediate cavities from the orbit. In most Birds a 
small intermediate vacuity is partitioned off from the nostril by a process of the maxillary 
rising to join the nasal, and is similarly separated from the orbit by the lacrymal, which 
descends to join the malar. The great range of variety in the development of this 
‘ intermediate ’ or " antorbital vacuity,’ in Pterosauria, has already been pointed out ; but 
• ‘Zur Fauna der Vorwelt,’ fol., 1860, p. 16. 
2 See Cuvier, ‘ Osseinens fossiles,’ v, pt. 2, pi. xvi, fig. 1 (‘grand Monitor du Nil, Lacerta nilof.ica'), 
p. 259, the Varanus Draccena of Merrem, Varanus niloticus of most modern erpetologists ; also in pi. xvi, 
fig. 7, ‘ Monitor du Java,’ p. 260 ; the Varanus bivittatus, of Merrem. 
^ As e.g. Tupinambis teguixin, ‘ Sauve-gai-de d’Amerique.’ Cuvier, vol. cit., pi. xvi, figs. 10, 11, and 
Thorictes Braccena, ih., figs. 12, 13 ; ‘La Dragone,’ ib., p. 263. 
