30 



PART I. GENERAL ACCOUNT 



mts — 



Fig. 20. Siboglinum pellucidum. The fore-part of the body in dorsal view. Pinnules are absent. 

 с - cephalic lobe ; со - dorsal ciliated band ;f~ bridle ; ms - mesoma ; mts - metasoma ; ps - protosoma ; 

 s 1 - groove between the protosoma and the mesosoma ; s 2 - groove between the mesosoma and the 

 metasoma; t - tentacle. (After Ivanov, 1957a.) 



The two highest families of pogonophores — the Lamellisabellidae and the 

 Spirobrachiidae — are distinguished by the firm longitudinal adhesion of the 

 tentacles, of which only the distal ends remain free and detached. Each 

 tentacle is stuck to the next by a substance which covers the cuticle. In 



