b'd.c.--basidorsal cartilage (neural arch) b'oc.--basioccipital ce._{1-4}--centrale_{1-4} ch.--ceratohyal clav.--clavicle clei.--cleithrum cor.--coracoid d.c._{1-4}--distal carpal_{1-4} diap.--diapophysis exoc.--exoccipital ep.--episternum hyost.--hyostapes i.--intermedium Mk.--Meckel's cartilage n.--notochord om.--omosternum op.--operculum opis.--opisthotic par.--parietal par. proc.--paroccipital process peri. cent.--perichordal centrum p'p.--postparietal prep.--prepollex pro.--prootic p'sp.--parasphenoid pt.--pterygoid p.t.f.--post-temporal fossa postzyg.--postzygapophysis qj.--quadratojugal qu.--quadrate ra.--radiale r.hy.--hyomandibular ramus of VII rib-b.--rib-bearer r.md.--mandibular ramus of VII sc.--scapula sc'cor.--scapulocoracoid s'd.--supradorsal cartilage s'd.(postzyg.)--supradorsal (postzygapophysis) soc.--supraoccipital sp.c.--spinal cord sq.--squamosal s'sc.--suprascapula s't.--supratemporal sta.--stapes ster.--sternum tab.--tabular uln.--ulnare v.a.--vertebral artery xiph.--xiphisternum I,IV--digits I and IV V, VII, X, XII--foramina for cranial nerves of these numbers (in Fig. 4, VII is the facial nerve) ] In temnospondylous Amphibia the tympanum generally occupied an otic notch, at a high level on the skull, bordered dorsomedially by the tabular and ventrolaterally by the squamosal. In this position the tympanum could receive airborne sounds whether the animal were entirely on land or lying nearly submerged with only the upper part of its head exposed. Among those Anura in which the ear is not reduced the same is true, except that the tabular is lost. In Temnospondyli (Fig. 3) the posterior wall of the otic capsule was usually formed by the opisthotic, which extended up and outward as a buttress from the exoccipital to the tabular, and sometimes showed a paroccipital process for the insertion, presumably, of a slip or tendon of the anterior axial musculature. The stapes, in addition to its foot in the fenestra ovalis and its tympanic or extrastapedial process to the tympanum, bore a dorsal process (or ligament) to the tabular, an "internal" process (or ligament) to the quadrate or an adjacent part of the squamosal, and a ligament to the ceratohyal. Some of these attachments might be reduced or absent in special cases, but they seem to have been the ones originally present both phylogenetically and embryonically in Amphibia.