LIASSIC FORMATIONS. 
61 
to the unbiassed investigator, and, indeed, becomes plainly his business, to determine, not 
merely whether Avian or Saurian characters predominate in the Pterosaurian skull, but to 
define the degree of affinity or correspondence of cranial structure therein traceable to 
such structures in Enaliosauria, JDinosauria, Bicynodontia, Crocodilia, Lacertilia, each of 
which may be a group, organically, of co-ordinate value with Aves. 
Greater respect to the memory of so unbiassed a seeker after truth cannot be shown 
than by weighing with due care and what judgment one may be able to bring to the task 
the value and significance of each well-determined evidence of the cranial structure which 
VoN Meyer has described and reasoned upon. 
It is to be regretted that not in any of the numerous figures of the skull of Ptero- 
original or copied, has Von Meyer indicated the bones which he describes. When 
he writes — “ The temporal bone lies external to the parietal and principal frontal bones, 
and mainly forms the temporal fossa,” ^ one much wishes he had indicated his ‘ Schlafen- 
bein ’ in the skull of Pltamphorhynclms Gemminyi, pi. hi, fig. 4 ; pi. ix ; pi. x, fig. 1 j 
or in the more instructive example of cranial structure which he has borrowed from 
Goldfuss for the subject of his pi. v {Pterodactylus crasdrostris) . 
By ‘ Schlafenbein ’ Von Meyer may mean that element of the compound ‘temporal 
bone’ of anthropotomy which I have called ‘squamosal.’ No doubt in Man and 
most Mammals the squamosal does contribute a notable share to the formation of the 
temporal fossa, whence the name ‘ temporal ’ given to the incongruous group of cranial 
elements coalescing in such warm-blooded Vertebrates with the squamosal, so exceptionally 
expanded in the Mammalia. But as to the value of the bed of the temporal muscles in 
determining the homology of the bones forming it, I would refer to the remarks in my 
work on the ‘ Homologies of the Vertebrate Skeleton.’ ^ 
Some clue to the bone signified by Von Meyer may be got from the following remarks — 
“ Anteriorly it seems not to take, as in Birds, a share in the formation of the orbital rim ; 
here, much more as in Saurians, it is pushed aside or supplanted by the postfrontal.” ^ 
The terra ‘ temporal bone ’ (Schlafenbein) has been used in various senses, but 
whether it be applied to that element which I, with Cuvier, call ‘ mastoid ’ in Peptilia, 
or to that which others,^' with Cuvier, call ‘temporal’ (meaning squamosal) in Birds, 
there is no bone that Von Meyer can be supposed to mean by ‘Schlafenbein^ which 
forms any part of the rim of the orbit in Birds. 
Von Meyer recognises a ‘ postfrontal’ (‘ Hinterstirnbein ’) in Pterosauria, and states 
that it pushes away his temporal (Schlafenbein) from the orbit. In Pterosauria the post- 
1 “ Das Schlafenbein liegt aussen an dem Scheitelbein und Hauptstirnbein, und bildet hauptsachlich 
die Scblafengrube.” — Op. cit., p. 15. 
2 8vo, 1848, p. 33. 
3 “ Vorn sclieint es nicht wie in den Vogeln an der Bildung des Augenbblilenrandes Tlieil zu nehmen, 
bier vielmehr wie in den Sauriern durch das Hinterstirnbein verdriingt zu werden.” — Op. cit. p. 15. 
^ Hallman, “Die vergleichende Osteologie des Schliifenbeins,” p. 8, pi. 1. 
