. On the anatomy of vertebrates [electronic resource] . vertebral ribs articulate over the in-terspace of their own and the antecedent centrum; a smalltubercle defines the neck of the rib, save in the last four; but,save in the first and second, does not articulate with the dia-pophysis. The first dorsal pleurapophysis is broad, the othersare cylindrical and slender; cartilage is interposed between thebony pleur- and hasm-apophyses of the anterior dorsal vertebras,as in the Crocodile. The sternum consists of four bones inOrnithorhynchus, and of five in Echidna. The first, fig. 199, s,is an unu
. On the anatomy of vertebrates [electronic resource] . vertebral ribs articulate over the in-terspace of their own and the antecedent centrum; a smalltubercle defines the neck of the rib, save in the last four; but,save in the first and second, does not articulate with the dia-pophysis. The first dorsal pleurapophysis is broad, the othersare cylindrical and slender; cartilage is interposed between thebony pleur- and hasm-apophyses of the anterior dorsal vertebras,as in the Crocodile. The sternum consists of four bones inOrnithorhynchus, and of five in Echidna. The first, fig. 199, s,is an unusually expanded (manubrium, receives the hasmapo-physes of the first and second ribs, and supports a large T-shaped LXXIX. p. 375. SKELETON OF MONOTREMATA. ,117 episternum, ib. t The sacrum consists of two vertebras inOrnithorhynchus, and of three in Echidna. There are thirteen caudal vertebras in the Echidna, fig. first is the largest, with broad transverse processes, the restprogressively diminishing, and reduced, in the six last, to the 201. Skeleton of Echidna, lxxiii/ central element. The Ornithorhynchus, fig. 199, has twenty-onecaudal vertebras, of which all but the last two have transverseprocesses, and the first eleven have also spinous and articularprocesses. The pleurapophysial parts of the transverse processesare distinguishable in half-grown animals. The transverse pro-cesses are broad and depressed; they gradually increase in lengthto the tenth caudal, then as gradually diminish to the twentieth;their extremities are expanded, and, from the fifth backward, arethickened and tuberculate. The spinous processes progressivelydiminish in height from the first caudal. Hypapophyses aredeveloped from the bodies of the third to the nineteenth caudalvertebra inclusive ; but there are no hasmapophyses articulated tothe vertebral interspaces, as in many Marsupials. In the Echidnahypapophyses are absent; but rudiments of hasmapophyses areconnected with the interspaces of
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