320 



PART II. SYSTEMATIC ACCOUNT 



Big D 



an 



Fig. YY133. Siboglinum sergeevi: A - front end of the body from the ventral side; В - fore-part of 

 the body from the dorsal, and C, from the ventral side; D - region of the girdles from the left; 

 E - part of the postannular region from the right. 



an- girdles; с -cephalic lobe; со - dorsal ciliated band; /-bridle; pa- papillae; ^-groove 

 between the protosoma and mesosoma; s % - groove between the mesosoma and metasoma; s 4 - post- 

 tentacular groove; sc - dorsal shield; sv - ventral sulcus; t - tentacle; v - ventral papilla. 



