588 



ALEXANDER MEEK 



displayed in all the sections figured. This is the disposition 

 of the septum in the branchial region, but with the disappear- 

 ance of the gills the septum is extended medially to be attached 

 to the upper part of the post-branchial alimentary canal. 

 It is obvious, therefore, that in the branchial region of the 

 body the septum forms a cavity for the inner branch of 

 the gonad, and that this cavity excludes this branch of the 

 gonad from the space between the dorsal wall of the body 

 and the branchial region of the ahmentary canal ; or, to 

 put it another way, from the space between the dorsal 



Text-figs. 12 and 13. 



nurse 

 bodies 



Qonopore 



margin 

 ye/7. Yiirlff 



dorsal ressel gill pore gen. groove 



- gill 



' septum 



tongue 



sperms 



■fC ^wTOB ttt^ \\ 



12 



13 



Fig. 12. — A more detailed view of a section of the margin of the 

 genital wing through the gonopore. 



Fig. 13. — Section through a gill-pore of the right side to show dis- 

 position, the gill skeleton in section with synapticula, and the 

 insertion of the lateral septum to the genital groove. 



genital groove and the dorsal mesentery. The gill-pores 

 are, therefore, not merely medial to the gonopores, they are 

 medial to the gonad. The outer lobe could certainly pene- 

 trate this region but it does not do so. It is only behind the 

 branchial region that the displacement of the septum to the 

 wall of the gut permits of the inner branch of the gonad 

 invading this region of the body cavity. This is a feature of 

 importance, for it is the disposition of the septum and the 

 gonad in the genus Glossobalanus, and it has been discussed 

 by Spengel in the monograph and in his paper on Gloss o- 



