. On the anatomy of vertebrates [electronic resource] . MY OF VERTEBRATES. maxillary bones, and encroaches a little upon the palatines. InManges Dasyure there are two large ovate apertures crossing the palato-maxillary sutures se- 222 parated from each other by a have already noticed the large vacuities which occur in the bonypalate of nearly all the Marsupials; but this imperfectly ossifiedcondition is most remarkable in the Perameles lagotis, in which,fig. 222, the bony roof of the mouth is perforated by a wide ovalspace extending from the second premolars to the penultimatemolars, exposing
. On the anatomy of vertebrates [electronic resource] . MY OF VERTEBRATES. maxillary bones, and encroaches a little upon the palatines. InManges Dasyure there are two large ovate apertures crossing the palato-maxillary sutures se- 222 parated from each other by a have already noticed the large vacuities which occur in the bonypalate of nearly all the Marsupials; but this imperfectly ossifiedcondition is most remarkable in the Perameles lagotis, in which,fig. 222, the bony roof of the mouth is perforated by a wide ovalspace extending from the second premolars to the penultimatemolars, exposing to view the vomer and the convolutions of theinferior spongy bones in the nasal cavity. The pterygoids, , 24, long maintain their individuality ; and repeat the connec-tions they present in Birds. The parietes of the cranial cavity are remarkable for theirthickness in some of the Marsupial genera. In the Wombat thetwo tables of the parietal bones are separated posteriorly for theextent of more than half an inch, the interspace being filled with. broad plate of bone ; posterior tothese are two apertures of similarsize and form, which, being situ-ated nearer the mesial line, aredivided by a narrower osseousbridge; each posterior externalangle of the bony palate is alsoperforated by an oval the Viverrine Dasyure thetwo vacancies which cross thepalato-maxillary suture are in theform of longitudinal fissures, cor-responding to the fourth and fifthgrinders ; the posterior margin ofthe bony palate has four smallapertures on the same transverseline. Since the defective conditionof this part of the cranium is oneof the characteristics of the skullof the Bird, it might be ex-pected that some approximationwould be made to that structurein the animals which form thetransition between the Placentaland Oviparous Vertebrates. We Perameles lagotis. SKELETON OF MARSUPI ALIA. 347 a coarse cellular diploe; the frontal bones are about two and ahalf lines thick. In the Ursine Das
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