50 
Squamosum der Reptilien, Vögel und Säuger complet homolog ist. 
Dagegen ist bei den jetzt lebenden Amphibien kein Deckknochen vor- 
handen, der die Bezeichnung ‘Squamosum’ verdiente.” 
Of the squamosal of Teleosts VROLIK says (No. 33, p. 283), that 
it “constant den Can. semic. ext. einschließt”. He furthermore says 
(p. 229): “Mit dem Postfrontale zusammen bildet das Squamosum 
gewöhnlich das Gelenk für das Hyomandibulare. Den Namen Squa- 
mosum hat schon Sprx gebraucht. Dagegen deutet Cuvier diesen 
Knochen als Mastoideum der Schildkröten und Krokodile, das mit 
dem Frontale posterius die Gelenkfläche bildet für das Hyomandibulare, 
dem CuvIER den Namen Squamosum zuteilte. MECKEL nannte das 
Frontale posterius Squamosum; darum deutet er unser Squamosum 
als mastoideum. HALLMANN giebt als Function des Squamosum an, 
daß es die Gelenkfläche des Hyomandibulare bildet; auch erwähnt er, 
daß es den Canalis semicircularis externus birgt. KÖSTLIN stützt seinen 
Namen Squamosum auf Vergleichung mit der Begrenzung und Lage 
bei Reptilien und Vögeln. Acassız nennt diesen Knochen Temporal, 
weil er ihn, seiner Begrenzung wegen, nicht für ein Mastoideum halten 
kann.” 
Huxtey, or perhaps first PARKER, proposed for the squamosal 
of fishes the name pterotic, and of it HuxLey says (No. 19, p. 26): 
“It lies on the upper and outer part of the ear-capsule between the 
proötic and the epiotic.” Of the bone in Esox he says (loc. cit. p. 133): 
“The postero-external [process of the primordial cranium] closely cor- 
responds with the squamosal of the higher Vertebrata in position; 
but, as a cartilage bone, it corresponds with an ossification of the 
capsule of the ear, called pterotic in the higher Vertebrata.” PARKER 
says of it (No. 24, p. 96), that it is an ossifying tract that “begins. 
over the ampulla and arch of the horizontal canal”. 
In Amia the squamosal was described by BrIDGE (No. 7) as a 
parietal. The true parietals of the fish, which, in the specimen BRIDGE. 
examined, were found fused with each other in the middle line of the 
head to form a single median bone, were considered by him as a 
dermo-supraoccipital. The outer margin of each so-called parietal 
was said by him to fulfil “the function of a supratemporal in trans- 
mitting the cephalic continuation of the main lateral slime-canal”. 
Two separate and independent, so-called supratemporals, one on each 
side of the head, were however described by him. They are the 
extrascapulars of SAGEMEHL’s descriptions (No. 27) and my own. 
The squamosal of Amia, as both Brincge and SAGEMEHL have 
stated, rests upon the primordial cranium only along its lateral edge, 
