268 



TELEOSTOMI 



The foramen magnum is bounded by paired exoccipitals at the 

 sides, and a median basioccipital below. In the Teleostei (Figs. 

 305, 381) a median supraoccipital appears above (p. 326). The 

 exoccipitals, which are pierced by the glossopharyngeal, the vagus, 



sm. 



obs. O f 



FIG. 237. 



Ania calva, L. (After Allis, slightly altered.) A, left-side view of the skull. B, left-side 

 view of the cranium, from which the dermal bones have been removed. Cartilage is dotted. 

 a.c, auditory capsule ; an, adnasal ; ar, dermarticular ; as, alisphenoid ; 60, basioccipital ; bst, 

 branch! ostegal ray ; c, cartilaginous cranium ; d, dentary ; ep, epiotic ; eth, mesethmoid ; ex, 

 exoccipital ; /, frontal ; fa, foramen for facial nerve ; ff, foramen for vagus ; h, hyomandibular ; 

 iop, interopercular ; I, lachrymal ; in.g, median gular ; m.l, lateral line in mandible ; inx, 

 maxilla ; n, neural arch ; lui, nasal ; n.sp, neural spine ; o, opisthotic ; obs, orbitosphenoid ; 

 oc.n, foramen for spino-occipital nerve ; o./, vacuity with optic foramen in front ; olf, olfactory 

 capsule ; op, opercular ; p, parietal ; pf, prefrontal ; pmx, premaxilla ; po, prootic ; pob, post- 

 orbital ; pop, preopercular ; pp, supratemporal ; pt, post - temporal ; ptf, postfrontal ; q, 

 quadrate; s, pterotic ; s.a, supra-angular; sm, septomaxillary ; so'p, subopercular ; apm, supra- 

 maxilla ; t.f, trigeminal foramen ; v.c, vertebral centrum. 



and the occipito - spinal nerves, replace cartilage of compound 

 segmental origin (p. 12). The basioccipital forms the floor of the 

 brain-cavity behind, develops round the anterior end of the noto- 

 chord, and corresponds to the vertebral centra situated farther back 



