Identifier: b20416039_001 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

View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book

Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image: e frontboundary and separates them from the nasal apertures, n. In ANATOMY OF VERTEBEATES. 157 Lizards, ib. D, the palatine 20, and pterygoid 24, form the medianboundary, the maxillary, 21, and ectopterygoid the outer one of y.In the Crocodiles, ib. c, the palatine 20 forms the median, theectopterygoid 25 the outer, the maxillary 21 the fore, and the ptery-goid 24 with the ectopterygoid the hind, boundary. In the Che-Ionia there is no ectopterygoid to divide the pterygo-maxillaryvacuity from the lower opening of the temporal fossa. The nextopenings in point of constancy are the palatal, or posterior,or internal nostrils —f palatonares ; but they are variously formedand situated. In the Menopome, fig. 73, there is no palatine boneto divide them from the pterygo-maxillary vacuity ; in fig. 98 A,the Frog, the transverse palatine forms the posterior boundaryof the palatonares, n, the vomer the inner, and the maxillary theouter, boundary; they are similarly encompassed in the Lizards, 98

Text Appearing After Image: Frog. Tortoise. Crocodile. Iguana. Palatal apertures, Eeptilia. ib. D, n. In the Crocodiles, the palatonares, ib. C, n, form a singleaperture surrounded by the pterygoids, and situated far back.There is also a single premaxillary foramen, ib. C, p, at the forepart of the bony palate. This is sometimes divided into two by thepremaxillary, like the external nostrils, as in the Iguana, ib. D, p.In most Lizards there is a more or less elongate 6 interpterygoidvacuity, ib. D, s, bounded behind by the hypapophyses of thebasisphenoid, laterally by the pterygoids, and usually extendingsome way between the palatines. In the Mosasaurus the inter-pterygoid fissure does not extend far back between the pterygoids,but is bounded in a greater proportion by the palatines. Some-times there is a distinct small f interpalatine vacuity, ib. m, in 158 ANATOMY OF VERTEBRATES. advance of the inter pterygoid; and more rarely there occurs an6 intervomerine vacuity still more in advance. Thus there are definab

Note About Images