Elements of the comparative anatomy Elements of the comparative anatomy of vertebrates elementsofcompar00wied Year: 1886 'AKATIVi: ANATOMY. processes may unite with the corresponding ribs (Fig. 35). In the thoracic region, more or fewer of the vertebra- usually become immovably united together. 06 Ft . / /; rt vPsi IMC. 35. — THIKII CKKVK \i, \'Ki:Ti.\ OF 'VYoonrKcicKi: (/'<V•). (Viewed anteriorly.) >'«, articular surface of centrum ; Ob, upper arch ; TV/., articular process ; Pi, I'/, tin- two bars of tlic transverse process, shown on one side :incliylo<eil \\iih the <
Elements of the comparative anatomy Elements of the comparative anatomy of vertebrates elementsofcompar00wied Year: 1886 'AKATIVi: ANATOMY. processes may unite with the corresponding ribs (Fig. 35). In the thoracic region, more or fewer of the vertebra- usually become immovably united together. 06 Ft . / /; rt vPsi IMC. 35. — THIKII CKKVK \i, \'Ki:Ti.\ OF 'VYoonrKcicKi: (/'<V•). (Viewed anteriorly.) >'«, articular surface of centrum ; Ob, upper arch ; TV/., articular process ; Pi, I'/, tin- two bars of tlic transverse process, shown on one side :incliylo<eil \\iih the < -i-r\ 'ical rib (7,'j ; Ft, transverse (vortebrarterial) foramen ; Put, ha-mal spine. Mammalia. — No direct connection exists between the vertebra- of Reptiles and Birds and those of Mammals. The notochord persists longer intervertebrally than vertebrally, lint it disappears entirely by the time the adult condition is readn-d. A jelly-like pulpy mass, the nucleus pulposus, persists, however, throughout life in the centra of the EuSro-cartilaginous menisci which are developed between the vertebrae. Articulations between the centra are never formed, but, as in Amphibians, Reptiles, a ml Birds, well-developed articular processes are present, arising from the neural The cervical region is usually the rn<e-t moveable, and the centra may be so much hollowed out in tin- region as to give them an opisthoccelous character ( Ungulata). In some cases, on the other hand, the cervical vertebrae may become firmly fused together (Cetacea). The centra are provided with epi- physgs^ except in all but those of the caudal region of Monotremes and in Sirenia C?). The atlas and axis essentially resemble those of Birds, though the differentiation of the vertebral column into regions, characterised by difference of form, is much more sharply marked than in any other Vertebrates. In long-necked Un;_rulates (llnrsr, faim-l, Ox) the neural spines of Ilic .•interim- tli'--e-
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