The oral cirri of Siluroids and tlie otigin of the head in Vertebrate». 419 



fact that the Suspensorium possesses little mobility and the suspension 

 is little removed from autostylism, which I hold to be the primitive 

 condition. 



Of late years it has become customary to look upon the "Ganoids" 

 as derived from Selachii, while the Teleostei are regarded as a 

 flourishing offshoot from the least primitive of the Ganoids, Amia. 



When the Ganoids were established as a limited group by the 

 weight uf MüLLEii's authority, and further when the primitiveness of 

 Selachii was so strongly insisted on by Geqenbaur, it was but logical 

 to assume that a Selachian form gave rise to a Ganoid, and this in 

 turn to a Teleostean. 



However the Ganoids are now being given up as a natural group. 



Sagemeiil's work illustrates the progress of such views. This 

 author directly compared Amia with Selachii , and came to the con- 

 clusion that a form like Amia might be descended from an early 

 Notidanus-Uke shark. Then he proceeded to show that the Chara- 

 cinidae are closely allied to Amia, while a group including Siluroids, 

 Gymnotidae, Characinidae and Cyprinidae, must be founded under 

 the term Ostariophyseae, since they possess in common the remarkable 

 "Wehek's apparatus". No weight can then be assigned to characters 

 of the dermal armature or fins. Bridge and Haddon , also working 

 on Weber's apparatus, seem also to accept the modern origin of 

 Siluroids. 



Thus according to Sagemehl the Siluroids are to be derived from 

 Amia. Such a view seems to me inconsistent with all known prin- 

 ciples of comparative anatomy and geographical distribution. 



Any discussion on the affinities of the Siluroids would be in- 

 complete without reference to the paleontological evidence. 



Agas.siz classed the Siluroids, on account of their dermal armature, 

 with the Ganoids, from which they were removed by Johannes 

 MCller. Subsequently (1858 — 61) Huxley following up the investi- 

 gations of Pander, compared certain of the Siluroids with Cephal- 

 aspidae. "No one can overlook the curious points of resemblance 

 between the Siluroids, Callichthys and Loricaria, on the one hand, 

 and Cephalaspis, on the other, while in other respects, they may be 

 still better understood by the help of the Chondrostean Ganoids." 

 "I am inclined to place the Ceplialaspids provisionally among the 

 Chondrostei, where they will form a very distinct family." Ray Lan- 

 kester at the conclusion of his monograph on the Cephalaspidae 

 remarks: 'Tt cannot be too strongly asserted that these fishes are, 



