On the anatomy of vertebrates (electronic resource) (1866) (14568703708)

Identifier: b20416039_002 (find matches)

Title: On the anatomy of vertebrates (electronic resource)

Year: 1866 (1860s)

Authors: Owen, Richard, 1804-1892

Subjects: Anatomy, Comparative Vertebrates Fishes Reptiles Mammals Birds

Publisher: London : Longmans, Green

Contributing Library: Wellcome Library

Digitizing Sponsor: Wellcome Library

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nnections of thepremaxillaries, 22, and their deep and large alveoli for the singlepair of incisors, recall characters of Rodentia. The cranial suturesbecome obliterated ; but examination of the skull of a veryyoung Elephant (Indian) has enabled me to give the following SKELETON OF FROBOSCIDIA. 439 details:—The basioccipital is notched behind, and contributesthere the lower ends of the occipital condyles : it increases inthickness as it advances to form the flat rough surface forjunction with the centrum in advance (basisphenoid). There is arough depression on each side of the under surface for the inser-tion of the 6 recti capitis antici. The exoccipitals form small,inferiorly approximate condyles, fig. 295, 2, have no precondyloidforamina, and do not develope paroccipital processes : they meetabove to complete the foramen magnum. The superoccipital ismuch expanded, and supports two supplementary bones (inter-parietals) : it is deeply impressed by the insertion of the liga- 295 296

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mentum nuchee. The basisphenoid has coalesced with the ali-sphenoids, which are separated from their neural spine (pariet-als, 7) by the intercalated squamosals, g. The pterygoid processesare long, much expanded and excavated anteriorly, and are per-forated at their base. The alisphenoids are perforated by a wide6 foramen ovale. The basisphenoid when united with the pre-sphenoid receives air into the cells with which the bone, as itacquires vertical extent, is excavated. The vomer retains itscharacter as a vertical plate, fig. 296, 13. The orbitosphenoidshave coalesced with each other at their base, and also with theprefrontals (lamina3 mediae aethmoidei) : they are perforated by theoptic foramina, and notched posteriorly for the foramen rotundum. 440 ANATOMY OF VERTEBRATES. The portions of the olfactory capsule closing the anterior orificeof the cranial cavity form extensive cribriform plates. Thefrontal, fig. 295, 11, is excessively expanded by the air-cells, fig.296; its hind borde

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