550 DESCRIPTIONS OF ANNELIDS. 



eighteen spines, their points curving invariably inward (iig. 12). The 

 inner circle of spines arises from the base of the long spines, near the 

 bottom of the cup, and ai'e slightly curved towards the center (fig. 11). 



The collar- setae have two conical points at the head of the main shaft 

 (13). The uncini of the thorax have from six to eight teeth; those of 

 the abdomen are smaller, with the same number of teeth (figs. 14 and 15). 



The setse and uncini of this and the preceding species are so nearly 

 alike that they fail to be characteristic. 



Very thin and frail calcareous tubes in living sponges. 



Length of large specimen, 40'°'»; breadth, 2.5"*°'. 



Gulf of Mexico, latitude 27° 04' N., longitude 83° 21' 15'' W., 26 

 fathoms; station 2409, ten specimens (975). 



Hydroides protulicola, n. sp. 

 (Plate XX, tijr. 17. Plate xxi, figs. 18-23.) 



The branchiae are small, having from ten to twelve filaments with 

 long, naked ends; the pinnae are large. 



The opercula have about twenty six conical points forming the edge. 

 Twelve stout spines, with their points invariably bent outward from 

 the center, form the inner and prominent armature (fig. 18). These 

 spines have stout, decurved processes on their inner bases, correspond- 

 ing to the spines forming the iniier circle in the preceding species 

 (fig. 17). 



As compared with H. diantJms, the points at the head of the main 

 shaft are a little Irmger and not quite so stout, and have prominent 

 markings below them (fig. 19). 



The thoracic uncini, having from six to eight teeth, are much nar- 

 rower than the abdominal, which have five or six teeth (figs. 20 and 21). 



Found living in coiled tubes fastened to the tubes of Protula diomedew. 



Length of large specimens, 16™™; width, 2™™. 



Off Cape Hatteras, latitude 35° 42' N., longitude 74° 54' 30" W., 43 

 fathoms; station 2307, 20 specimens (972). 



Crucigeea, new gen. 



Serpulidse with the operculum infundibuliform and calcareo-carti- , 

 laginous, bearing radii more or less branched, Avith rounded apices 

 crenulating the periphery ; inner surfaces beset with conical teeth. 

 Peduncle with four digital processes just below the operculum, forming 

 a cross. 



Crucigera "Websteri, n. sp. 

 (Plate xxi, figs. 24, 25. Plate xxii, figs. 26-30. > 



The branchiae are composed of about eighteen filaments. 



The operculum is bell-shaped, with a strong peduncle; four digital 

 processes arise on the peduncle just below the cup and form a cross. 

 The disk is composed of a number of radii, branching so as to form fifty 

 well rounded apices (ligs. 24 and 25). The radii, on their inner sur- 

 faces, are armed with sliort, conical, horny teeth. 



