Contribution to the embryology of the lizard; With especial reference to the central nervous system and some organs of the head; together with observations on the origin of the vertebrates

THE embryology of the lizard has been investigated in parts by various authors, yet all the work done on the subject is hardly so complete as to warrant a monograph.Concerning the segmentation of the egg and the formation of the germ-layers we are indebted for our knowlcdgc to Bal?our,l H O ~~~~C I I Z , ~ and Weld07t.~Thcse earliest stages of development were lacking in the material collected by me, so that my work begins about the stage where that of BaL'fozir and Weldoit ended, and deals with the early development and differentiation of some of the organs.The most comprehensive contribution hitherto made to lizardembryology is that of Hoffirza72.Stmhl, in a series of articles in the Arch.f.Anat.u.Phys.(Anat.Abth.) '81-87, has described the relations of the amnion and some anatomical features, but his methods prevcnted him from entering upon details requiring a finer histological investigation.The material for the present investigations was collected by me while a member of the zoijlogical expedition generously equipped and sent to Abaco, Bahamas, W.I., by the Y o h s Uopkins U?ziversiQ.The specimens have been kindly identified for me by Prof. E. D. Cope.