48 



PART I. GENERAL ACCOUNT 



formed of two massive roots fused at the base — stout parallel brown or 

 black fangs, which appear to be apodematous outgrowths deeply penetrating 

 into the thickness of the pulvillus and into the epidermis of the papilla. These 

 roots run out from the plaque at an angle of с 45°, their ends directed 

 obliquely backwards into the papilla (Fig. ЪАВ). On external examination of 

 the whole structure (from the ventral side of the animal) these roots and their 

 common base may be seen by transparency, lying below the surface of the 

 plaque in a sort of horse-shoe whose ends curve backwards (Fig. Ъ\А). The 

 sides and hind edge of the plaque are free and may catch lightly onto the 

 internal surface of the tube. Thus the apodemes of the plaques of Lamellisa- 

 bella are nothing more than a specialized form of the hoop-shaped thicken- 

 ings of the front rim of the plaques of other Pogonophora (Ivanov, 1957a). 



Fig. 35. Structure of the adhesive papillae in the middle and hind parts of the trunk. A - section 

 through a papilla of Polybrachia annulate, from the thickened zone ; В - section of a papilla of 

 Lamellisabella zachsi from die postannular region of the metasoma. 



cp - cell which secretes the cuticular plaque ; cut - cuticle ; ep - epidermis ; mb - basement membrane ; 

 mc - circular muscle fibre ; ml- longitudinal muscle fibre ; mpa - muscle fibre of papilla ; p - cuticular 

 plaque; ton - tonofibrillae in epidermal cells. (After Ivanov, 1960a.) 



