ON THE VERTEBRATE SKELETON. 935 
or disturbing the connections of the true stylo-hyal (fig. 5, 28) with the epi- 
tympanic (2s@) from whjch it is normally suspended. 
M. Vogt correctly observes that the ‘temporal’ Sa 28a), ‘sym- 
plectique’ (mesotympanic, 2s 6), and ‘jugulaire’ (hypotympanic, 23d), “a 
eux seuls forment déja un arc suspensoir complet, 4 la face postérieure 
duquel le préopercule est seulement accolé*.” But this only proves that the 
preoperculum is an appendage to such arch, not that it is a suspensory pier 
of a second arch. 
The only essential modification which the siluroids present is the confluence 
of the preoperculum with the true tympanic pedicle, here reduced to a single 
piece. But this does not disprove its character as an appendage of the 
‘tympano-mandibular arch, any more than does the confluence of the ulna and 
radius with the scapular arch in the sturgeon disprove the character of those 
elements as appendages of that arch. I have not been able to trace in the 
siluroids the primitive boundaries of the coalesced preoperculum to such an 
extent as to justify the statement, that it is intercalated between the epitym- 
panic and hypotympanic, replacing the mesotympanic : but, if the preopercular 
should extend in any siluroid fish so far as M. Vogt describes, this excep- 
tional development would rather prove it to belong essentially to the tym- 
panic and not to the hyoidean arch: at least it is only through this abnor- 
_ mal encroachment that the preopercular can detach the stylohyal from the 
epitympanic. 
As the otosteals, or ‘ ossicula auditts,’ have borne a prominent share in the 
discussions of the special homologies of the tympanic pedicle and its append- 
ages, I may here remark that the extension in the embryo ‘mammal of the 
long and slender process of the malleus in the direction of the mandible, and 
its continuation or connection with the cylindrical cartilage (hemal portion 
of the tympano-mandibular arch) from which the lower jaw is subsequently 
developed, is a circumstance which renders the idea of the malleus, at least, 
being a modified element of the tympano-mandibular arch ia batrachians 
and fishes, worthy of consideration. The prolongation from the mesotym- 
panic of the cylindrical cartilage, described by Meckel, and around which 
the mandible is ossified in fishes, and the characteristic cylindrical or styloid 
form of the mesotympanic, have induced M. Vogt+ to view that bone, the 
*symplectique’ of Cuvier, as the homologue of at least part of the malleus; 
and at the same time of the bone called ‘tympano-malléal’ by Dugés (my 
‘hypotympanic’) in, the batrachians, M. Vogt offers no other reasons for 
‘the determination. | find that the cartilage which in the batrachians forms 
the medium of communication between the semi-ellipsoid ossicle (stapes) 
closing the fenestra ovalis and the tympanic membrane, is repeated or repro- 
duced in the more malleiform cartilage connecting the columelliform stapes 
of the saurian reptiles to the membrana tympani. In birds a portion of the 
cartilage attached to the tympanum becomes ossified and coalesces with the 
columelliform stapes; and at the angle of union one or two cartilaginous” 
processes exist, which some anatomists have compared with the incus. But 
all anatomists have concurred in recognising the homology of the peripheral 
bent-down portion of the long columella, which adheres to the membrana 
tympani, with the part of the malleus called ‘manubrium,’ or handle, in 
mammalia. The superadded modifications characteristic of the otosteals in 
this class, have their seat between the manubrium mallei and the stapes, and 
chiefly result in the development of the new bone called ‘incus’ and its epi- 
physis, which has been termed the ‘os orbiculare.’ Notwithstanding, there- 
_ fore, the connection of the ‘processus gracilis mallei’ with the embryonic 
* Annales des Sciences, 1845, p. 55. + Loc. cit. p. 58. 
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