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. 



Fig. in. 



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

 «/, spiral filament; n, nucleus of central filament. 



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

 development of the lasso-cells from, gc, gland cells and, <■/, filaments formed from, i?i, the 

 interstitial tissue. 



3. — Two otoliths of Bfro'c (after Samassa). n, nucleus. 



4. — Section tlirough the ectoderm cushion at the base of a comb. 73c, basal cells of the comb ; 

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



5.— Diagrammatic section through a comb. £c, basal cells ; cil, plate fonned of fused cilia. 

 (After Chun.) 



C. — Attachment of the radial muscles, rm, to the stomodafal sphincter muscles, rim, in lieroe. 

 (Afti-r Samassa.) 



7.— Epithelium of Cestux ivneris, .showing gland cells, glc ; in various stages of development 

 Imbeddeil in a coenocytial interstitial tissue, it. 



S. — Diagram showing the position of the ovaries, or, and the spermaries, t, in the hypoctenial 

 diverticula of the meriilional canals in Em-haris nuilticornis, and in Bnlina alata. 



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

 Bolina hi/datina. 



10. — Diagram of the tentacle ba.se of Hnrmiphora plumosa, after Chun, i, infundibulum ; 

 St, stomodaeum ; ste, stomodaal canal ; fr, 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 



