RELATIONS OF ANTERIOR VISCERAL ARCHES. 69 



v. Zittel, K. A. (C. R. Easman, Ed.). 



'02 Text Book of Palaeontology, Vol. II., Svo, 1902. 

 COLUMBIA UNIVERSITY, 



DEPARTMENT OF ZOOLOGY, 

 February 10, 1904. 



PLATE I. 



EXPLANATION OF ABBREVIATIONS. 



P. Q. , Palatoquadrate. H.M"., Median limb of ditto. 



Mck., Mandible (Meckelian cartilage). H.M"'., Posterior limb of ditto. 



H.M., Hyomandibular (epihyal). Sym., Symplectic. 



B.H., Basihyal. Q., Quadrate. 



C.H., Ceratohyal. P. Op., Preoperculum. 



P.H., Pharyngohyal. I. Op., Interoperculum. 



Sp.C., Spiracular cartilage. Op., Operculum. 



I.H., Inter- or stylohyal. S.Op., Suboperculum. 



Pal., Palatine. VII. , Aperture for seventh nerve. 



Ms. PL, Mesopterygoid (entopterygoid). h.s.l., Hyosuspensorial ligament. 



Pt. t Pterygoid. niJi.l., Mandibulohyoid ligament. 



Mt.Pt., Metapterygoid. St. , Stapes. 



H.M'., Anterior limb of hyomandibular. 



Cartilaginous elements stippled, osseous elements with small crosses. 



FIG. l. "Hyostyly proper." Centrophorus granulosus. Embryo. After Gadow. 



FIG. 2. " Hyostyly proper." Chlamydoselachiis anguinetts. After Garman. 



FIG. 3. " Euhyostyly. " Trygon sp. After Gadow. 



FIG. 4. " Amphyostyly." Heptane Jms ciner ens. Internal view. After Gadow. 



FIG. 5. " Methyostyly." Diagram of the relations of the suspensorial and oper- 

 cular regions in the cod. 



FIG. 6. Methyostyly. Polyplerus. View from within and below. The meta- 

 pterygoid is supported by the hyomandibular. 



FIG. 7. Cartilaginous basis of methyostylic arrangement in the young salmon. 

 After Parker and Bettany. 



FIG. 8. Cartilaginous basis of methyostylic arrangement in a larval siluroid. 

 After Pollard. All the cartilages of the suspensorial region seem to have secondarily 

 coalesced. 



FIG. 9. "Autostyly." Ceratodns. After Huxley. R, R' , vestigial hyoid rays. 

 The operculum is borne by the reduced hyomandibular. 



FIG. 10. "Autostyly." Protezts. After Gadow. The stapes represents the 

 upper portion of the hyomandibular (Gadow). 



FIG. II. " Holostyly " Chimizra collei. 



