436 
G. J. DE FEJERVARY 
named family, which makes it seem obvious that owing to the pelagic 
mode of life, this portion of the body was least liable to change, and 
therefore might furnish useful directions with regard to phyletical 
* connexion. I also make allowance for the fact 
of the structure of the skull decidedly sug¬ 
gesting that of Platynota, although merely 
a suggestion ! According to Williston 1 
the jugal arch is incomplete, though not 
much phyletical importance can be attributed 
to the fact ; for, in my opinion, the jugal 
a r c h being complete or incomplete represents 
a mere quantitative and no qualitative 
conception. I have thus, within the genus Vara- 
nus, lighted upon a complete jugal arch in a 
skull of V. salvator Laur., whilst the skull of other 
species and individuals presented an incomplete 
jugal arch. 2 Certain ligaments through inactivity, 
easily become cartilaginous, and later on ossify 
by the effect of age ; this being often the ex¬ 
planation of the jugal arch being complete or in¬ 
complete. Exactly the same phenomenon is met 
with as regards the complete or incomplete 
temporal arch of certain species of Molge, 
and I even had the opportunity of observing a 
most interesting — and undoubtedly rare — 
similar case on the skull of Rana esculenta subsp. 
ridibunda Pall. (coll. Dr. Bolkay), where owing 
to ossification of the ligament between processus 
zygomaticus and the maxilla, an almost entire 
bony arch was formed; we also sometimes find 
examples of such ligamentous ossifications on 
the nasal bones of Frogs, such phenomena are 
besides frequently met with in anatomy in gene¬ 
ral. Too much importance cannot therefore be 
attached to such slight digressions. Much more 
1 Fide Nopcsa, in: Üb. d. varanusart. Lac. Istriens, Beitr. z. Pal. n. Geol. Őst. 
Ung., Bd. XV, Wien u. Leipzig, 1903. 
2 About Aigialosaurus Boulenger writes as follows (op. cit. 206): «. . . with 
somewhat the physiognomy of a monitor or Varanus, but with the jugal in contact with 
the postfrontal and closing the orbit behind»; this, as stated above, does not seem to be 
an important character as regards p h y 1 e t i c value. 
