THE CTENOPHORA 



within the tentacle sheath, a wide sac-like invagination of the 

 ectoderm. The tentacular base is the broad proximal extremity of 

 the tentacle, and is inserted on the inner or axial side of the 

 tentacular sheath. It is penetrated by a pair of saccular cavities 

 which are prolongations of the transverse gastrovascular canals. 



1C. 



Fio. III. 



1. Two lasso-cells (after Samassa). gl, glandular portion of lasso-cell ; c/, central filament ; 

 sf, spiral filament ; n, nucleus of central filament. 



2. Section through the epithelium of the base of a tentacle of Hormiphora, showing the 

 development of the lasso-cells from, gc. gland cells and. c/. filaments formed from, in, the 

 interstitial tissue. 



3. Two otoliths of Beroe (after Samassa). n, nucleus. 



4. Section through the ectoderm cushion at the base of a comb. Be, basal cells of the comb ; 

 p, their processes ; cp, connecting process going to the next comb. (After Samassa.) 



5. Diagrammatic section through a comb. Be, basal cells ; til, plate formed of fused cilia. 

 (After Chun.) 



6. Attachment of the radial muscles, rm, to the stomodseal sphincter muscles, rim, in Beroe. 

 (After Samassa.) 



7. Epithelium of Cestus veneris, showing gland cells, glc; in various stages of development 

 imbedded in a coenocytial interstitial tissue, it. 



8. Diagram showing the position of the ovaries, ov, and the spermaries, t, in the hypoctenial 

 diverticula of the meridional canals in Eucharis multicornis, and in Bolina alata. 



9. Diagram showing the position of the ovaries and spermaries in Deiopea kcdoktenota and 

 Bolina hydatina. 



10. Diagram of the tentacle base of Hormiphora plumosa, after Chun, i, infundibulum ; 

 st, stomodaeum ; stc, stomodseal canal ; tc, tentacular canal ; a/, accessory filament ; m, 

 muscles ; tsh, tentacle sheath. 



The partition between the tentacular canals is called the tentacle 

 stem; it contains muscles which converge from the wall of the 

 tentacle sheath to the tentacle itself, where they form a solid axial 



