94 



VERTEBRATE SKELETON 



itals; the lateral members of this row are often called supra tem- 

 porals, but that they are the homologues of the supratemporals of 

 Tetrapoda is doubtful. All Teleostomes, a few Teleosts excepted, 

 have the pectoral girdle connected with the cranium by the supra- 

 cleithrum articulating with the epiotic as mentioned above, and 

 often with the opisthotic as well, by two heads, the supracleithrum 

 then appearing as a cranial bone (posttemporal) . In front, the 

 cranium may have the mesethmoid cartilage or bone covered by a 

 derm- or supraethmoid bone. 



Fig. 99. — Lateral view of skull of Amiurus (Kindred, '19). ar, articulare; as, 

 alisphenoid; ee, ectethmoid; ept, epipterygoid; /, frontal; hm, hyomandibula; io, inter- 

 operculum; /, lacrimal; m, maxilla; mpt, metapterygoid; n, nasal; op, operculare; pa, 

 palatine; pf, postfrontal; pm, premaxilla; po, postorbital; pop, preoperculum; pt, 

 pterotic; q, quadrate; sbo, suboculars; se, supraethmoid; so, supraoccipital; sph, spheno- 

 tic; st, subtemporals. 



The lateral hne canals nearly surround the eye, and bones may 

 develop around them (fig. loo), called, according to position, supra-, 

 pre-, post-, and sub- or infraorbitals. Some of these may be traced 

 with some certainty in Tetrapoda, and it would appear that the 

 postorbitals are the homologue of the single postorbital of higher 

 groups; the anterior and posterior supraorbitals as pre- and post- 

 frontals, while one of the antorbitals is apparently the lacrimal of 

 Tetrapoda. It is not so certain that the zygomatic is the equivalent 

 of the piscine suborbitals. 



The roof of the Teleostome mouth (fig. loi) is formed by, in 

 front, a pair of (frequently toothed) vomers, followed by a long 

 parasphenoid bone which extends across the floor of the skull and 

 back to the basioccipital, and may bear teeth, an additional evidence 

 of its origin (p. 7). 



