XIII 



PHYLUM CHORD AT A 



127 



and the great ring-shaped annular cartilage (an. c.) which supports 

 the edge of the buccal funnel. 



GL.d.C 



B 



nc7t 



Cft.C 



FIG. 795. Petromyzon marinus. Dorsal (A), ventral (B), and sectional (C) views of skull. 

 The cartilaginous parts are dotted, a. </. c. anterior dorsal cartilage ; an. c. annular cartilage ; 

 au. c. auditory capsule ; b. cr. /. basicranial fontanelle ; b. pi. basal plate ; en. c. cornual 

 cartilage ; cr. r. cranial roof ; n.a. neural arch ; na. ap. nasal aperture ; nch. notochord ; Nv. 1, 

 olfactory nerve ; Nv. 3, 5, and 8, foramina for the optic, trigeminal, and auditory nerves ; 

 Nv. 5', fifth nerve ; off. c. olfactory capsule ; p. <L c. posterior dorsal cartilage ; p. lat. c. posterior 

 lateral cartilage ; si. oc. a. sub-ocular arch ; st. p. styloid process. (After W. K. Parker.) 



The " tongue" is supported by a long unpaired lingual cartilage 

 (Fig. 794, Iff. c.), which probably answers to the united Meckel's 



