22 



penetrates the cartilage [Stannius ^)]. A stylohyal or hyosuspensorial 

 cartilage does not seem to be differentiated in the hyosuspensorial 

 ligament ^). A similar state of things is seen in the Siluroid Chaeto- 

 stomus and in certain Urodeles ^). Gadow^) has attempted to homo- 

 logize the hyosuspensorial cartilage of Urodeles with the symplectic. 

 I cannot agree with his conclusion. 



It may be added that the distal cartilages of the operculum and 

 interoperculum as described by Huxley are represented in a South 



Fig. 5. 

 Pterotic Begion 



Op. c.~\L y-y 



Sty.hy.--" yk/^ ^ --- -- Mck. 



American Siluroid Trichomycterus by a sheet of procartilage in the 

 posterior edge of the opercular fold. 



Polypterus (Fig. 5). The suspension of the jaws in Polyp terus 



1) Stannius, Peripherisches Nervensystem der Fische, Rostock 1849. 



2) According to most authors. In the specimen at my disposal closer 

 inspection revealed a small cartilage in the ligament probably represen- 

 ting a stylohyal. 



3) On this point see Cope, Journal of Morphology, Vol. II, 1888 — 89. 



4) Gadow, Phil. Trans., 1888. 



