M. M. METCALF ON THE EYES AND SUBNEURAL GLAND OF SALPA. 339 



relation to that of the latter. Salpa costata-Tillesii shows features 

 of resemblance to each of the members of the cylindrica group, and 

 at the same time shows features of difference from each. It is hard 

 to say to which it is most closely related in the structure of the eyes, 

 though in the position of its smaller eyes it most nearly approaches the 

 cyclosalpas. 



The relationships toward which the comparative anatomy of the 

 eyes of the different species would point are graphically expressed in 

 the following table. The reason for placing Salpa Africana-maxima as 

 the most primitive of the cylindrica group will appear when we take up 

 the subneural gland. 



DIAGRAM 1 . 



C. pinnata. 

 C. Cham. 



S. cyl. 



. dem.-muc. 



S. cost. -Till. 



S. cord.-zon. 



S. runc.-fus. 

 S. Af.-max." 



\, 



.S. bicaiul. 

 -S. scut.-conf. 



This table does not pretend to show the actual relation between 

 species, but rather that relation toward which the evidence derived 



