FiuLD. — Prouepbroj iu Amphibia. 



PLATE I. 



Fig. 1. A portion of a cross section through the anterior trunk region of one 



of the older embryos included under Stage I. X 110. 

 " 2. A cross section through the same embryo in the middle trunk region. 



X 25. 

 " 3. A portion of a cross section through the middle trunk region of one 



of the younger embryos in Stage I. X 02. 

 " 4. A portion of a cross section through the hinder trunk region of one of 



the younger embryos belonging to Stage II. X 02. 

 " 5. A portion of a cross section through the anterior trunk region of one of 



the older embryos from Stage II. The section passes through an 



interprotovertebral septum. X 110. 

 " 6. A portion of a cross section from one of the older embryos in Stage III. 



The plane of the section passes through the middle of Somite III. 



X no. 



" 7. A small segment of a cross section through the embryo shown in Figures 

 15-17 of Plate II. The Figure represents a portion of the ventro- 

 lateral ectoderm with three subjacent mesodermal cells. X G15. 



" 8. A portion of a cross section through the embryo shown in Figures 18-22, 

 Plate III. It shows the fundament of the glomus. X 110. 



" 0. A portion of a cross section through a slightly older embryo, showing 

 the glomus in a more advanced stage of development. X 110. 



" 10. A portion of a cross section through an embryo of Stage V., showing 

 a branch of the aorta which gives off a small vessel to the glomus. 

 X 150. 



