180 AN ELEMENTARY TEXT-BOOK OF BIOLOGY. 



case is covered by the pamsphenoid, a dagger-shaped bone, with 

 its " blade " running forwards. 



Sense Capsules. Two pairs of these are fused with the skull, 

 (a) auditory capsules behind and (ft) olfactory capsules in front. 



(a ) The auditory capsules are closely fused with the hind end of 

 the brain-case, one on each side. They are largely cartilaginous, 

 but each is invaded behind by the ex-occipital of its side, while 

 in front the cartilage is replaced by a large pro-otic bone, which 

 also assists to form the side- wall of the brain-case, and is notched 

 below by the trigeminal foramen, through which the trigeminal 

 and facial nerves pass. The auditory capsule contains a complex 

 cavity, in which the essential organs of hearing are contained. 

 On its outer side is a depression, in which is a small opening, the 

 fenestra ovalis, filled up with membrane in the recent state. 

 Another and smaller opening on the hinder border, the fenestra 

 rotunda, is filled up in the same way. 



Fig. 50. ENDOSKELETON or FROG (A, A', and C, after Ecker). Cartilage 

 dotted. A and A', Skull from above and below, membrane bones being 

 stripped off on one side; /, /', fontauelles; f.m, foramen magnum; 

 ex-oc, ex-occipital ; c, condyles ; v.f, vagus foramen ; pr-o, pro-otic ; 

 t.f, trigeminal foramen; op.f, optic foramen; g-b, girdle bone; orb, 

 orbit; ol, nasal capsules ; e-p.b, ethmopalatine bar ; pt. b, pterygoid bar ; 

 sp, suspensorium ; q-j, quadrato-jugal; pt, pterygoid; pa-f. parieto- 

 frontals ; p-s, parasphenoid, half cut away ; sq, squamosal ; na, nasals ; 

 v, vomer; pr-mx, pre-maxilla; mx, maxilla; pi, palatine; e.n, external 

 naris ; i.n, position of internal naris. B, Columella, enlarged. p and d, 

 Ends fitting into fen. ovalis and fixed to tymp. membrane, respectively. 

 C, Left half of Mandible, from outside. m-mk, Mento-meckelian ; c, 

 condyle; a-sp, angulo-splenial ; d, dentary. D, Hyoid apparatus. 

 b-hy, Body of hyoid; a.c, anterior cornua; br, remains of branchial 

 arches. E, Spinal Column and Pelvis (top view). Numbers refer to 

 vertebrae, and are placed near transverse processes. ust, Urostyle; il, 

 ilium; is, ischium; ac, acetabulum. F, Various Vertebrae. 1, Atlas, 

 front view; 2, side view of two adjacent vertebrae; 3, back view of 

 vertebra; c, centrum; n.s, neural spine; t.p, transverse process; a-z, 

 pre-zygapophysis ; p-z, post-zygapophysis ; n. c, neural canal ; i.f, inter- 

 vertebral foramen. G, Side View of Pelvis. il, Ilium; pb, pubis; is, 

 ischium; ac, acetabulum. II, Sternum, Shoulder Girdle, and Fore-limb- 

 (Ventral View). o-s, Omo-sternum; st, sternum proper; x-st, xiphi- 

 sternum; gl, glenoid cavity; s-sc, supra-scapula; ep-co, epi-coracoid ; 

 pr-co, pre-coracoid sheathed by clavicle ; h, humerus ; hd, head of ditto ; 

 d.r, deltoid ridge; r-u, radio-ulna ; ra, radiale; wZ, ulnare; en, centrale,- 

 c 1-5, carpalia; I-V, metacarpals; 1-5, phalanges. I, Hind Limb, dec. 

 (ust, urostyle, &c., as before)./, Femur; hd, head of ditto; t-f, tibio- 

 fibula; as, astragalus; ca, calcaneum; t, 1-3, tarsalia; I-V, metatarsals; 

 1-5, phalanges; *, placed by calcar. 



