1886.] PROCEEDINGS OF ttNITED STATES NATIONAL MUSEUM. 549 



Protula alba, n. sp. 

 (Plate xs, figs. 8,9.) 



Branchiae spiral of about one turn ; filaments, twenty-five. When the 

 branchise are removed at the base two dark spots are exposed to view, 

 as described by Stimpson as a character of P. media. 



The thoracic lamellae are broad and very thin, continuous with the 

 collar, which is entire. 



The setae of the thorax are long and slender, outer third limbate. 

 The uncini of the thorax and abdomen are alike in form; their teeth are 

 exceedingly minute (fig. 8). The falcate setae of the abdomen have also 

 very minute teeth on their inner edges (fig. 9). The extreme jjosterior 

 abdominal setae are of the usual form, long, hair-like, and curved at the 

 ends. Color white. 



Length of large specimens 25™'"; breadth of thorax, including lamellae, 

 gmm. breadth of abdomen 2.5™'". 



Saint Thomas, West Indies; shallow water. Ten specimens (979). 



Hydroides Gunner. 



Hydroides dianthus Verrill. 

 (Plate XX, fig. 10.) 

 Serpula dianthus Verrill, Invert. Animals of Vineyai'cl Sound, p. 620, 1874. 

 Hydroides dianthus Verrill, Proc. Acad. Nat. Sci., Phila., for 1878, p. 300. 

 Hydroides dianthus Webster, Auuel. Chajt. of the Virginian Coast, p. 06, 1879; and 

 Annel. Chset. of New Jersey, p. 28, 1879. 



The branchiae are comi>osed of about eighteen filaments. There are 

 three concentric circles of spines on the operculum, the outer one being- 

 formed by the denticles on the edge. These denticles are from 21 to 27 

 in number, short and pointed, curving outward from the center. The 

 next circle is composed of ten long spines (ten on four specimens and 

 nine on one), curving either outward from the center or towards it; in 

 none of the specimens examined did more than five point outward. 

 The third and inner circle is composed of short conical projections 

 arising from the base of the long spines of the second circle (fig. 10); 

 these conical projections or spines are close down to the tloor of the 

 operculum, and are usually concealed by dirt. 



The only color remaining is a wide band of dark green a little below 

 the edge of the operculum. 



Tubes convoluted, calcareous, on living oysters, shells, and stones. 



Five small specimens from the oyster beds of Chesapeake Bay (997). 



Hydroides spongicola, n. sp. 

 (Plate XX, figs. 11, 12. Plate xxi, figs, 13-16.) 



Branchiae large, composed of about thirty slender filaments. 



Operculum armed with three concentric circles of spines, the outer 

 one on the edge of the operculum comprising sixty-five slender-pointed 

 denticles curving outward from the center. The next and most ]>romi- 

 nent circle arises from inside the cup of the operciilnm and extends 

 upward perpendicularly to the floor; it is composed of from fourteen to 



