244 BULLETIN OF THE BUREAU OP FISHERIES. 



Crab Ledge, in 14 to 20 fathoms, not common, two colonies on a shell of Alodiolus modiolus in United 

 States National Museum collections, labeled "Vineyard Sound, 1875, station 4708." 



Genus RHAMPHOSTOMELLA Lorenz, 1886. 



Among the other genera of this family,, Rhamphostomella may be easily distinguished by the 

 presence of the large orifice, together with a prominent mucro which bears an avicularium on the side. 

 The zooecial wall is generally thin and delicate. 



KEY TO SPECIES. 



1. A single suboral rostrum 2. 



Two projections behind the orifice, one of which, usually larger, bears the avicularium . . . .bilaminata. 



2. Rostrum high, surface of zooecium strongly ribbed costata. 



Rostrum not so high, surface not strongly ribbed ovata. 



Rhamphostomella bilaminata (Hincks). [PI. xxvi, fig. 61, 6ia.] 



Hincks 1877, p. 30 (Cellepora bilaminata}. 



Verrill and Smith 1873, p. 714 (Cellepora scabra pars). 



Verrill 1879!], p. 195, and 18790, p. 30 (Mucronella scabra pars). 



Whiteaves 1901, p. 108. 



Zoarium encrusting hydroid stems, etc., often rising into small fan-like or shelf -like expansions. 

 Zooecia large, the walls thin and glassy, imperforate, convex above, occasionally more or less radiately 

 ribbed, but the ribs do not run up on the rostrum; orifice very large, rounded or irregular in front, 

 straighter behind, with a small denticle centrally placed, the thin peristome rises behind the orifice 

 into a double fold with a deep notch between the lip-like projections, and through this notch the denticle 

 is visible; the median lateral surface of one of these projections bears an avicularium, though the avicu- 

 larium is occasionally wanting and rarely there is one on each side of the notch. Ooecium hemispherical, 

 smooth and punctured, very large, usually obscuring hah" of the aperture of the cell and the base of the 

 cell in front as far as the rostrum; when fully calcified a rib or margin often rises about the base of the 

 ovicell. 



Taken at a number of points in Vineyard Sound and Buzzards Bay; common at Crab Ledge and 

 Great Round Shoal. VerriU's references to Cellepora scabra include both this species and R. costata, 

 as I have determined by a study of his specimens. I believe, however, that VerriU's record "Vine- 

 yard Sound and Quicks Hole" refers to bilaminata alone, since it is more common in the region than 

 costata and is the only one I have observed in the inner waters of the Sound and Bay. The species ranges 

 northward to Greenland. 



Rhamphostomella costata Lorenz. [PI. xxvi, fig. 62, 62a, 62b, pi. xxxi, fig. 100.] 



Lorenz 1886, p. 12. 



Hincks 1889, p. 426. 



Whiteaves 1901, p. 108. 



?Verrill and Smith 1874, p. 714 (Cellepora scabra, pars). 



Verrill i879b, p. 195, and 18790, p. 30 (Mucronella scabra, pars). 



Zoarium encrusting stems of various sorts, forming frill-like or fan-like expansions which rise free 

 to a height of a half inch or more. Zooecia large, the walls thin, glassy and imperforate, convex above 

 and rising very rapidly to the base of a very high, large rostrum; there is a row of areolae around the 

 margin and between these there are strong radiating ribs which run up on the rostrum; orifice very 

 large, rounded in front, straighter behind with a small tooth in the middle; peristome very thin and 

 without oral spines in our specimens; the rostrum is enormously developed, the costal ribs run up on it, 

 and it bears on its antero-lateral face a large pointed avicularium with the mandible turned upward; 

 occasionally a large pointed avicularium on the front wall of the cell. Ooecia very large, usually ob- 

 scuring half of the orifice and the base of the cell in front to the base of the rostrum; surface smooth, 

 punctured. 



