An introduction to the study of the comparative anatomy of animals . le of a certain amount of flexion, in virtue of the articula-tions of the centre and arches of its component vertebra. Thecolumn, especially its neural and transverse processes, servesfor the attachment of some of the most important muscles ofthe trunk. The skull is articulated to the first vertebra by two pro-minences, known as the occipital condyles, which fit into itstwo concavities. The skulls of all the craniate vertebrates (by which wemean those vertebrate animals which have a distinct head)present certain features in c
An introduction to the study of the comparative anatomy of animals . le of a certain amount of flexion, in virtue of the articula-tions of the centre and arches of its component vertebra. Thecolumn, especially its neural and transverse processes, servesfor the attachment of some of the most important muscles ofthe trunk. The skull is articulated to the first vertebra by two pro-minences, known as the occipital condyles, which fit into itstwo concavities. The skulls of all the craniate vertebrates (by which wemean those vertebrate animals which have a distinct head)present certain features in common, and though that of thefrog is peculiar in some respects, it is fairly illustrative of thefundamental features of all skulls. A skull comprises the following parts : (i.) A brain case orcranium proper; a cartilaginous or bony, or, as in the frog,partly cartilaginous, partly bony, box, which contains the the back of the brain-case is a large aperture, the foramenmagnum, by means of which the spinal cord passes into the brain. Digitized by Microsoft®. Fig. I. The skull and vertebral column of the Frog, viewed from the dorsal ^ The same from the ventral surface. C, Lateral view of the urostyle ; a bristleis passed through the foramen for the tenth spinal nerve. D, The branchialskeleton of the Frog. (AH the figures after Ecker.) O, orbital fossa; pnix,premaxilla ; vix, maxilla ; g-j, quadrato-jugal; na, nasal; fif, parieto frontal;rfx, exoccipital; fr}i^ foramen magnum ; pro^ pro-otic ; sg, squamosal; sp. et,sphenethmoid; par, parasphenoid ; pal, palatine ; vo, vomer; ptg; pterygoid;av, atlas vertebra; c, centrum; ar, neural arch; zyg; zygapophysis ; trv, trans-verse process; ur, urostyle ; H, body of the hyoid; Ha, anterior cornu ; Hp,posterior cornu of the hyoid. Digitized by Microsoft® 26 COMPARATIVE ANATOMY (2.) The sense capsules, of which there are three pairs. Theolfactory capsules, which contain the organs of smell, aresituated anteriorly; the audi
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