310 



Profs. T. W. Bridge and A. C. Haddon. [June 20, 



species of Siluridae, referable to about fifty genera, and mainly belong- 

 ing to Dr. Giinthers sub-families of Siluridae Homalopterae, S. Heter- 

 opterae, S. Proteropterae, and S. Proteropodes. For the present we 

 shall only give a brief resume of the morphological variations in 

 the structures concerned, leaving their physiological bearing and 

 the more general conclusions which the facts elucidated suggest, 

 to a future and more detailed communication to this Society ; 

 but before doing so we venture to suggest the need of a revision of 

 the customary nomenclature of the so-called "auditory ossicles." 

 From a mistaken idea of their homology with the Mammalian au- 

 ditory ossicles, Weber gave to three of them the suggestive but 

 extremely misleading names of "incus," " malleus," and "stapes." 

 Since Weber's time, however, it has become obvious that the 

 " auditory " ossicles of the Ostariophyseae are in no sense homologous 

 with the similarly named bones of the Mammalian tympanum, and it 

 is almost equally clear that the two series of ossicles have nothing 

 in common with regard to their respective functions. With a view 

 of avoiding all possibility of the confusion which may result from 

 applying identical terms to structures widely different in origin and 

 probably equally remote in function, we venture to suggest a different 

 nomenclature for the " auditory ossicles " of Weber. Instead of 

 stapes we propose the name " scaphium," in allusion to the invariably 

 concavo-convex or spoon-shaped form of this ossicle. The "incus" 

 may be renamed the " intercalarium," from its constant intermediate 

 position between the "stapes" and the "malleus," when present. 

 For " malleus " we would substitute " tripus " — a name suggested by 

 the three characteristic processes which this ossicle invariably 

 possesses. The fourth ossicle, called the "claustrum" by Weber, 

 forms one of the series of auditory ossicles in the Cyprinoid fishes, 

 but has no such physiological significance in the Siluridae, although 

 it is very generally present. As the name "claustrum" is open to 

 none of the objections which can reasonably be urged against the reten- 

 tion of Weber's nomenclature of the three preceding ossicles, it may 

 with advantage be retained. For the ossicles collectively, including 

 the claustrum, and for obvious reasons, we would suggest the name 

 " Weberian ossicles " as an appropriate designation, instead of " audi- 

 tory ossicles." 



In summarising the more noteworthy of the results of our investi- 

 gations into the morphology of the air-bladder and Weberian ossicles, 

 and the correlated modifications which the anterior vertebrae and their 

 processes undergo, we may indicate, in the first instance, such 

 features as appear to be common to nearly all Siluroids, and secondly, 

 those that are characteristic of particular genera or species. 



Although only demonstrated in one particular instance (the young 

 of Amiurus catus) by Ramsay Wright, our researches lead us to 



