Information about osteological changes in the groups of reptiles that gave rise to mammals is preserved in the fossil record, but the musculature of these reptiles has been lost forever. Nevertheless, a reasonably accurate picture of the morphology and the spatial relationships of the muscles of many of these extinct vertebrates can be inferred by studying the scars or other marks delimiting the origins and insertions of muscles on the skeletons... more...

DEVELOPMENT OF THE DIGESTIVE CANAL OF THE AMERICAN ALLIGATOR By ALBERT M. REESE Professor of Zoology, West Virginia University In a previous paper () the writer described the general features in the development of the American Alligator; and in other papers special features were taken up in more detail. In the present paper the development of the enteron is described in detail, but the derivatives of the digestive tract (liver, pancreas,... more...