PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1886. 



EXPLANATION OP PLATE XXIV. 



SpiroirancJius giganteus (Pall.) Morch. 



Fig. 4:^. Straight collar setae, enlarged 210 diameters. 

 Fig. 44. Bent collar setae, enlarged 210 diameters. 

 Fig. 45. Thoracic uncinus, enlarged 650 diameters. 

 Fig. 46. Abdominal uncinus, enlarged 650 diameters. 

 Fig. 47. Abdominal s&tai, enlarged 325 diameters. 



Spirobranchus incrassatiis (Kroyer) Morch. 



Fig. 49. Operculum, enlarged. 



Spirobranchus dendropoma Morch. 



Fig. 57. Abdominal setae, enlarged 325 diameters 

 Fig. 58. Thoracic setae, enlarged 325 diameters. 



