EXPLANATION OF PLATE V. 



EUN4CEA MURICATA. 



Fig. I. Transverse section {greatly enlarged) of branch f reserved in alcohol: a, 

 axis cylinder; b, its sheath; c. c, primary water- vascular canals; d, 

 secondary water- vascular canals ; e, e, e, e, spaces from which spicules 

 have been dissolved; f, f, f, f, f, epidermis; g, g, g, endodermal lining 

 of calicles; h, h, h, retracted tentacles of polyps; i, i, opercular mus- 

 .cles; j, j, j, j, retractor muscles; k, k, convoluted gullet; 1, 1, 1, mesen- 

 terial filaments; m, m, m, m, ova. 



Fig. 2. Tratisverse section of primary tvater-vasciilar canal shoiving lining of 

 endodermal or endothelial cells. 



