2G4 
PROFESSORS T. W. BRIDGE AND A. C. HADDOX 
transmitted to the scapliiimi requires a more critical examination than lias yet been 
given to this point by previous writers. Although of considerable thickness in pro- 
portion of its length, the interossicular ligament cannot be regarded as a rigid 
structure, but rather as being more or less compressible, and hence the immediate 
result of any slight inward movement of the anterior process of the tripus towards the 
scaphium, following upon any outward bulging of the corresponding lateral wall of 
the anterior chamber, will be the compression of the ligament in the direction of the 
length of its component fibres, and this must necessarily lead to an outward bulging 
or swelling analogous to that of a contracting muscle, the swelling taking place at 
right angles to the direction in which the force tending to produce compression is 
applied. Under .such circumstances, no immediate inward movement of the spatulate 
process of the scaphium takes place. Conversely, any slight outward movement of 
the tripus that might subsequently take place would at first only have the elfect of 
straightening, as it were, by a pull, the outwardly bulging fibres of the ligament. 
Hence, it may be concluded that relatively slight incursions or excursions of the 
anterior process of the tripus will produce no effect on the scaphium, and that only 
movements of the tripus, of greater amplitude than those now under consideration, are 
competent to bring about corresponding movements of the scaphium, or affect the 
fluids of the internal ear. But, apart from the interossicular ligament, there are other 
reasons for the belief which we certainly entertain, that the Weberian ossicles are but 
ill-adapted for the transmission of movements caused by the slight inward or outward 
bulging or vibration of the lateral walls of the anterior chamber. The size of the 
Weberian ossicles, or at all events, of the tripus; the character of the articulation 
between the articular process of the tripus and the centrum of the third vertebra, 
which, in some Siluridae {e.g., Auchenipterus nodosus and A. ohsciirus) is effected by 
the actual but flexible continuity of that process with the centrum in question ; and 
the fact that all movements of the ossicles, or at least of the tripus, must take place 
in the loose, fluid-infiltrated connective tissue of the saccus paravertebralis — seem to 
afford strong additional evidence that the Weberian apparatus is far better adapted 
to register the more forcible, even if more gradual distensions or contractions of the 
anterior chamber, rather than slight or rapidly recurring vibrations of its lateral 
walls. Among other facts tending to the same conclusion may be mentioned the 
extreme thickness of tlie walls of the air-bladder in many Siluroicls, and in certain 
genera and species {Osteogeniosus, ^lurichthys, and several species of Arius), this 
feature is still further emphasized by the development of vertically-disposed, buttress- 
like, aggregations of the fibres forming the inner stratum of the tunica externa of the 
lateral walls of the anterior chamber. The peculiarities of the interossicular ligament 
and the inertia of the Weberian ossicles, taken in conjunction with other anatomical 
features more directly pertaining to the structure of the air-bladder itself, seems to 
us to offer an insuperable objection to any theory of the function of those ossicles 
which relies upon their capacity to be affected by, or to transmit to the internal 
