AVIAN CESTODES. 873 



embryo. There is no great difference in size between the egg- 

 holding cavities in the two genera. But there is an important 

 difterence in the structure of the wall of these cavities in Diplo- 

 pylidium, and in the presently described genus Eugonodcettm. In 

 Diplopylidium I was unable to find any nuclei lining the cavities, 

 which are simple excavations in the medullary tissue. This was 



Text-fis. 148. 



c- 



\ A. 



\ 



\ D. 



■ I 



Another part of the same section of JSugonod<eum oedicnemi showing older embryos 

 surrounded by a greater egg-holding cavity in tlie medullary parenchyma. 



A, B. Egg surrounded by thick shell and lying in cavity from which nutritive 

 cells (?), such as are shown at e s. in text-figure 147, have disappeared. 

 C. Older embryo with larger space surrounding it. D. A degenerating (?) 

 egg-holding cavity and embryo. 



the case, not only with the fully mature embryos, but also in com- 

 paratively newly formed cavities. In Eugonodceum, on the other 

 hand, the egg-holding spaces possess a lining of cells. It is true 

 that in fully mature embryo-containing cavities these cells are 



