SPIROBRACHIA GRANDIS 



447 



papillae: in a female about 220 pairs of 

 more or less metameric papillae were 

 counted (Fig. 170). For a considerable 

 length the metamerism is rather strict, 

 but falters after a time, so that while the 

 66th papilla on the left lies opposite the 

 66th on the right, the 139th on the right 

 lies opposite the 138th on the left. 

 Farther back the metamerism begins to 

 break down completely. The papillae 

 are crowded close together (Fig. Ill A) 

 and in the hind part of the metameric 

 region they form conical mammillae, 

 rather sharply delimited from the sur- 

 face of the trunk (Fig. 172C). On their 

 tips they bear round or pear-shaped pul- 

 villi with cuticular plaques (Fig. 1725). 

 The ventral sulcus does not extend 

 to the end of the metameric part but 

 peters out at the level of the 95th-100th 

 pair of adhesive papillae. The dorsal 

 ciliated band is broad (Fig. 1715) and 

 extends in the female to the level of the 

 61st pair of papillae. The cuticular 

 plaques are large (1 10/j. across) and their 

 anterior thickened part is represented 

 by a flat curved hoop, whose ends are 

 cut off square (Fig. 1 72/)). In the second 

 half of the metameric region the plaques 

 are larger still (up to 190)u) and their 

 hoops are more drawn out (Fig. \12E). 

 The region of the girdles and the post- 

 annular section of the body remain 

 unknown. 



/■ / 7 ' 



Fig. 170. Spirobrachia grandis: Front end of a female from the right side. Part of the tube has not 

 been dissected away. 



с - cephalic lobe;/- bridle; ms - mesosoma; wts - metasoma; p - cuticular plaque; pa - metameric 

 papillae; tc - tentacular crown; tub - part of the tube. (After Ivanov, 1952.) 



