BY R. BROOM. 



717 



relatively longer than in Enibr3'o C, is considerably narrower, as 

 is also the upper part of the great intestine generally. The 

 rectum is now distinctly open. 



Urin»genital system. — The mesonephros is relatively very large, 

 and the tubules very much convoluted. The Muellerian ducts 

 are laid down for a very short distance. The germinal epithelium 

 is well developed, but sexual differentiation is not apparent. The 

 condition of the permanent kidney is very similar to that in 

 Embryo C; the sprouting is, however, somewhat more marked. 



Embryo F (14 mm). Plate xxiii., fig -5. 



This embryo has already been figured by Dr. Beard in the 

 paper above referred to, liut as his illustration is not very care- 

 fully done, and contains a number of inaccuracies, I have thought 

 it well to refigure the embryo. This and the following embryo 

 well illustrate the degree of development just before birth. The 

 epitrichial layer is so far developed that the eye and ear are 

 almost completely obscured : the position of the eye, however, 

 can be distinctly made out owing to the pigmentation still being 

 visible through the epithelial layer. In Dr. Beard's illustration 

 a certain obscure shading is evidently intended to represent the 

 position of the eye, but the eye is consideraljly nearer the nostril 

 than is indicated in the drawing. The lips are almost united 

 laterally to form the " Saugmund," but not yet completely. The 

 head is still folded slightly on the chest. The arms and hands 

 are in much the same position as in the earlier embryos —folded 

 across the chest. The claws are now well developed. The hind 

 limbs are still small, though the digits are very distinctly formed 

 and partly separated from each other. The hallux stands 

 prominently out and about equals in size the 2nd and 3rd digits, 

 while the -tth and 5th digits are each about one-half larger than the 

 others. In Dr. Beard's figure the 2nd and 3rd digits are shown 

 as fairly large, and the 4th and 5th quite rudimentary. 



Epidermis. — The epitrichial layer is fairly well developed over 

 the whole body, but is especially marked on the snout, sides of 

 head, and fore-limbs. Hair follicles are present in those situa- 



