572 B. F. Kingsbury and 11. D. Reed. 



that take place in the ear capsule in Triton. The presence of a 

 rudimentary columella seems clearly established. The problem of its 

 phylogeny may be better discussed from a comparative view-point. 



No trace of a stilus or connection with the squamosum or pala- 

 toquadrate was to be found unless, possibly, a scanty group of cells 

 extending from the columella around the outer side of the vena 

 petroso-lateralis was its representative. 



In the adult Triton the conditions are much altered. The otic 

 capsule is strongly ossified ; the operculum being an oval plate of 

 cartilage filling in the relatively small fenestra vestibuli and pro- 

 jecting back a short distance. On its outer side it gives attachment 

 to a well developed M. opercularis; on its inner side is the cavum 

 perilymphaticum and its backward extension outside the otic capsule 

 is the recessus perilymphaticus. To the otic capsule behind and to 

 the edge of the fenestra the operculum is attached by membrane only. 

 The f enestral margin is osseous behind ; dorsal and ventral cartila- 

 ginous lips join to form the cephalic border of the fenestra, the ceph- 

 alic end of the operculum being slightly included. The columella is 

 completely merged with the otic capsule, though doubtless the dorsal 

 and cephalic cartilaginous margin of the fenestra, in part at least, 

 represents it. Figs. 43 (PI. V) and 44 (PI. VI) show the relations, 

 shape and cartilaginous consistency of the operculum. The latter 

 figure may be compared with Fig. 42 (PI. V) of Salamandra in 

 illustration of the more massive character of the operculum in that 

 form. Recurring again to the columella, in these two forms, Triton 

 presents a condition of much greater reduction and incorporation in 

 the absence (in the adult) of a recognizable f enestral plate and stilus 

 columella (cf. Figs. 41 and 43, PI. V). 



The development of the otic capsule in Triton has been followed 

 in more or less detail by Reichert '38, Semmer '72, Parker '82b, 

 Wiedersheim '77, and Stohr '79. From the reduced condition of 

 the columella in this salamander, it was to be expected that its 

 presence, not to mention significance, should be entirely overlooked 

 and that the development of the operculum should be given correctly 

 in all essential points. Hence we find Reichert, Semmer, Wieder- 

 sheim, Parker, and finally, Stohr describing the operculum as formed 



