Author Description

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 Excerpt:...are remarkable for their union with the broad costal plates of the carapace. Many of the Reptilia develop so-called abdominal ribs, which are ossifications of the connective tissue, and correspond to the ventral scales of Stegocephalians. The skull agrees more nearly with that of birds than amphibians in its general features, and the ossification of the primordial cranium is much more complete than in the latter group. The investing membrane bones are so intimately united with true cartilage bones that a distinction is often impossible. The basioceiput articulates with the atlas by means of a single, sometimes tripartite condyle, formed either by the basioccipital alone, or by this bone in conjunction with the exoccipitals. Both the basioccipital and supraoccipital may be excluded from the borders of the foramen magnum. Of the bones forming the auditory capsule, the prootic (petrosal) is situated in front of the lateral parts of the occipital region; it occurs as a separate bone, and its front margin is pierced for the third branch of the trigeminus nerve. The opisthotic is often fused with the exoccipital, and the epiotic with the supraoccipital. Besides the usual auditory opening, orfeneslra oral is, there is commonly & fenestra rotunda; the position of the former is either between the exoccipitals, or between the opisthotic and prootic. At the base of the skull immediately in front of the basioccipital occurs the basisphenoid, a true cartilage bone, in place of a parasphenoid; and this is continued in front by the presphenoid. Alisphenoids and orbitosphenoids are as a rule wanting, or are replaced by downwardly directed processes of the parietals and frontals. The lastnamed bones are usually of large size, and may be either paired or unpaired. Applie...