PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. L IH-O. 



EXPLANATION OF PLATE XXV. 



Spirobranchus denilropoma Morch. 



Fig. 50. Portion of brancliial iilamcnt, eularged. 



Fig. 51. Operculum, front view, eularged. 



Fig. 5'2. Operculum, side view, eularged. 



Fig. 53. Operculum of a large specimen, enlarged. 



Fig. 54. Collar setue, enlarged (>50 diameters. 



Fig. 55. Thoracic uncinua, eularged 050 diameters. 



Fig. 5(>. Abdominal uuciuus, eulixrged G50 diameters. 



