602 B. F. Kingsbury and H. D. Keed. 



its stilus with the squamosum is now reported^'^ for Necturus 

 maculatus, Proteus, Typhlomolge, Typhlotriton, Spelerpes bis- 

 lineatus and ruber, Gyrinophilus prophyriticus, Hemidactylium 

 scutatum, Plethodon cinereus, Stereochilus marginatus, Autodax 

 lugubris, Manculus quadridigitatus, Desmognathus fusca, Ambys- 

 toma punctatum, Chondrotus tenebrosus, Cryptobranchus allegbeni- 

 ensis, Megalobatrachus maximus. 



In certain of the forms, however, at transformation, — before or 

 after it, — the connection of the stilus tends to shift to the palato- 

 quadrate, presumably in the change of the position and direction 

 of the suspensorium to which Wiedersheim called attention ('77). 

 In this displacement of parts as we interpret it, the squamosum, as 

 in Ambystoma, comes to lie more on the dorsal surface of the palato- 

 quadrate. In certain forms a special process of the palatoquadrate 

 develops (e. g., Plethodon, Amphiuma) which may reach a rela- 

 tively great length (Amphiuma). Hence we see how the more 

 obvious connection has become accepted as the typical one, and the 

 primary connection with the squamosum^'' is overlooked, even though 

 occurring throughout life as the direct articulation in many of the 

 forms. If the anatomical relation of parts is such that the palato- 

 quadrate does not come into the proximity of the distal end of the 

 stilus in the shifting, a connection with it is not established, — as in 

 the case of Cryptobranchus (young adult) where the connection of 

 the stilus moves from the caudal edge to the under side of the 

 squamosum. Whether the stilus columellse maintains the primary 

 relation with the squamosum or becomes more closely joined to the 

 palatoquadrate, any physiological value it may possess as a "sus- 

 pensorial connection" remains unaffected, so closely is the lower 



"Cope, '89, describes the con-ect condition in Necturus and Proteus (p. 22) ; 

 of the remaining urodeles he says: "The stapes [colunielhi] has no connec- 

 tion with the suspensorium in the adult except in the Cryptobranchidse and 

 Amphiumidae. It is connected with the suspensory cartilage, which is con- 

 tinuous with the quadrate cartilage in the latter families, and In the young 

 of other Urodela" (p. 29). 



"The development of the stilus columellfe has not been studied in Sala- 

 mandra, nor in Amphiuma has the earliest development been yet worked out 

 (see Kingsbury, '03, p. 325). The squamosal connection will doubtless be 

 found in all salamanders possessing a well developed stilus. 



