60 
The intercalar of fishes was considered by HuxLery as the homo- 
logue of the opisthotic of higher animals, and most writers have since 
accepted this interpretation of it. As already stated in an earlier 
publication (No. 3, p. 21), my work leads me to doubt the correctness. 
of this interpretation and to accept VROLIK’s statement that the bone 
does not belong to what he calls “integrirende Teile des Schadels” ; 
that is that it is not a true otic bone. The intercalar of Amia is. 
said by SAGEMEHL to be of primary origin, but I have already had 
occasion to express my opinion that he was wrong in this conclusion,. 
and that the bone in this fish is wholly of membranous origin (No. 2, 
p. 688). In the Characinidae SAGEMEHL says (No. 29, p. 557) that 
the central part of the bone is, in all probability, of primary origin, 
but that the posterior point or process of the bone is of membranous 
(“metaplastische”) origin. This membranous point or process of the 
bone is said to be always present, and to give attachment to a liga- 
ment connected with the pedicle of the suprascapular. The bone is 
said to be in process of reduction, and in certain of the Cyprinidae 
it is said to have finally wholly disappeared. In his work on the 
Characinidae this reduction of the bone is said by SAGEMEHL to be 
due to the reduction of the pedicle of the suprascapular, to which the 
process of the intercalar gives attachment, and the bone, as it dis- 
appears, is said to be replaced by the squamosal. In his work on the 
Cyprinidae he concludes that the cartilaginous part of the intercalar 
is first displaced and replaced by the encroaching squamosal, and that 
the dermal part of the intercalar, although unaffected by this encroach- 
ment of the squamosal, later diminishes, independently, in size, 
and finally disappears, with the reduction of the pedicle of the supra- 
scapular. The bone is then specially referred to as an example of a 
bone, originally of unquestionably primary origin (Amia), which 
becomes, by gradual reduction (certain Teleosts), a purely dermal one, 
and then finally disappears. The bone in Amia was considered by 
SAGEMEHL as the homologue of the opisthotic of higher animals 
(No. 27, p. 188). 
The exoccipitale of SAGEMEHL’s descriptions and my own, is, like 
many other bones of the skull of fishes, known under several different 
names. It was called by HuxLry the epiotic, and was said by him 
to be developed in relation to the posterior vertical semicircular canal. 
As the occipitale externum it is said by VROLIK to be of “perichondro- 
stotische” origin, to be developed in relation to the insertion of muscles, 
and not to belong to the “intergrirende Theile des Schädels”. Of it, 
and of the supraoccipital and the squamosal also, he says (No. 33, 
p. 276), they form “fünf für das Hinterhaupt der Teleostier charakte- 
