590 B. F. Kingsbury and H. D. Reed. 



pre-cartilage, forming neither from the otic capsule nor the fenestral 

 membrane, but independently lying primarily anterior to the fenestra. 

 She suggested at this time the possible homology of the urodele 

 operculum with the pars interna plectri which is supported in this 

 paper; but evidently without much faith in its correctness, for in a 

 footnote in which she states her objection to the term "operculum" 

 she adds that this cartilage (operculum, i. e., columella) is not the 

 equivalent of the "columella" (plectrum) of the Anura and is of 

 questionable homology with the "stapes" of higher vertebrates. 



Kingsbury ('03) examined the early development in Necturus. 

 He confirmed Miss Piatt's results and in addition described the 

 primary connection with the squamosum and the cells underlying it: 

 "At this stage, the operculum is just beginning to chondrify as a 

 distinct center, and from it a chord of cells is continued forward, 

 ventral to the vena jugularis and the ramus jugularis, to the cells 

 surrounding the developing squamosum, becoming continuous wath 

 them a short distance (50 microns) back of the processus oticus 

 quadrati. The cells are of course continuous with those of the 

 squamosum and also with the cells between that bone and the 

 quadratum, so that the squamosum, the qu'adratum, and the liga- 

 ment-anlage, may be said to be joined together by a common mass of 

 cells. In the just hatched larva, likewise, the ligament-anlage 

 clearly goes to the underside of the squamosum and inserts itself 

 between that bone and the processus oticus quadrati, so that it 

 might be interpreted as going to both structures. As soon as the 

 connective tissue fibers develop, however, the relation is seen to be 

 with the squamosum and not with the quadratum. In later stages 

 a strong ligamentum squamoso-columellare develops, which connects 

 the stilus cohimellse to the columellar process of the squamosum." 



Wilder ('03) in a monograph upon the Skeletal System of Wec- 

 turus takes, however, a different view. He regards the operculum 

 (columella, our term) as a "detached portion of the otic capsule" 

 basing his view upon the condition in a 44 mm. larva which was 

 essentially the same as in a 26 mm. individual examined by him. 

 In the light of the work by Stohr on Triton and Siredon he regards 

 the statements of Miss Piatt as unfounded, admitting, however. 



