Richard Owen, Esq., on Comparative Osteology. 331 



vertebrse. Cervical, dorsal, sacral, caudal. Ribs and sternum. 

 Fixation of the trunk. Length and flexibility of the neck related 

 to want of prehensile power of the anterior extremities, to the func- 

 tions of the beak and the position of the food. Analysis of the 

 pelvis of birds : homologies of its constituent bones : utility of the 

 separation and elasticity of the pubic bones. Relation of the anchy- 

 losed and expanded caudal vertebrae to flight. Determination of the 

 bones of the scapular arch ; os humero-scapularo ; modifications of 

 the bones of the wing, and especially those of the segment corre- 

 sponding to the hand in relation to flight. 



Bones of the leg : determination of the tarsus, metatarsus, and 

 toes. Analogy between the metacarpus and metatarsus. Numeri- 

 cal relations of the toe-phalanges : their constancy exemplified in the 

 didactyle foot of the ostrich. 



Summary of physiological relations of the bones of the trunk and 

 extremities in birds. 



Lecture xii. — Osteology of Birds continued, — The skull; its spe- 

 cial characters and relations to the habits and exigencies of the class. 

 Smooth sutureless cranium ; its fossse and foramina. Advantages 

 of the single occipital condyle. Moveable articulation of cranium 

 with face. Mechanism for such motion by the " ossa quadrata," 

 " homoidea," and " communicatia" of Ornithotomists. Varieties in 

 the size and form of the upper and lower mandibles : their relation 

 to food and habits. Special homologies of the cranial bones of birds. 

 Determination of the mastoids and prefrontals. General homolo- 

 gies of the cranial and other segments of the skeleton, and their 

 relations to the archetype. Application of the osteology of recent 

 birds to the restoration of extinct species. Large and unexpected 

 accessions to Ornithology from these researches. Reconstruction of 

 DinorniSf Palapteryx, and Notornis. 



Antiquity of birds on the earth's surface shown by fossil foot- 

 prints or " Ornithichnites." 



Lecture xiii. — General characters of the class Mammalia. — 

 Characters of the sub-classes Implacentalia and Placentalia, and of 

 the implacental orders : Monotremata and Marsupialia. Principles 

 according to which the Placentalia are divided into the sections 

 Mutica, Ungulata, and Unguiculata ; and these into the orders 

 Cetacea, Sirenia, Perissodactyla, Artiodactyla, Edentata, Rodentia, 

 Insectivora, Cheiroptera, Carnivora, Quadrumana, and Bimana. 

 Osteology of the Monotrematous genera Ornithorhynchus and 

 Echidna ; Vertebrce of the trunk. Ossified sternal ribs. Persistent 

 *' vertebral" ribs in the neck. Analogy of lumbar and sacral Ver- 

 tebrae to those of Reptiles. Marsupial bones. Skull. Analogy of 

 smooth sutureless cranium with its ossified falx to that of birds. 

 Essential mammalian characters of the skull : homologies of the 

 cranial bones. Scapular arch. Bones of the fore- and hind-limbs. 



Lecture xiv. — Marsupialia. — Geographical distribution and 



