128 PROCEEDIlSrGS OF THE N'ATION'AL MUSEUM VOL.72 



The operculum is small, bell-shaped, with two lateral muscular 

 attachments; it is attached inferiorily to the compensatrix without 

 any trace of articulation. The mandible is triangular, dissymetric, 

 unguiculated. The retractor muscle is very large, flabelliform, and 

 formed of seven broad regular bundles. 



The zoarium is much ramified; the fronds are dichotomous and 

 develop like the horns of a deer. 



Biology. — The color varies from yellowish pink to orange (Osburn). 

 Our specimens are a yellowish gray. We have observed the expanded 

 base. 



Occurrence. — Albatross Station D. 2405, Gulf of Mexico; 28° 45' 



00" N.; 85° 02' 00" W.; 30 fms.; gray sand, broken 



coral. 



Fowey Light, 15 miles south of Miami, Fla.; 40 fms. 



Tortugas, 16-19 meters (Osburn); Florida, 16-77 



meters (Smitt) and 763 meters; Bermuda (Verrill). 



Plesiotypes.— Cat. Nos. 7461, 7462, U.S.N.M. 



Family HIPPOPODINIDAE Levinsen, 1909 



Genas METRARABDOTOS Canu, 1914 



METKARABDOTOS UNGUICULATUM, new species 



Plate 23, Figures 6-9; text Figure 26 



Description. — The zoarium is free, unilamellar, cylindrical, or con- 

 ical. The zooecia are distinct, separated by a thread placed at the 

 bottom of a furrow, large, much elongated, httle broad; the frontal 

 is convex, bordered laterally by areolar pores, formed of a pleurocyst 

 with large granules. The aperture is transverse, semielliptical, little 

 visible, arranged at the bottom of a peristomie. The peristomice is 

 orbicular and provided with a proximal sinus; the peristome is thick 

 and saUent. At the side of the aperture and adjacent to the peris- 

 tome there is a large falciform, long, thin, unguiculated avicularium 

 with its convexity oriented toward the base of the zooecium and the 

 beak toward the top. The ovicelled zooecia are much broader and 

 bear two very small oral avicularia. The ovicell is enormous, endo- 

 zooecial, convex, of the same structure as the frontal, and is orna- 

 mented with narrow, smooth, transverse callosities in the vicinity of 

 its orifice. 



(^a = 0.10 mm. 



Measurements. — Aperture (interior)^,, 



[to = 0.20 mm. 



TP, . ^ . iJiv = 0.20 mm. 

 reristomicei 7 ^^^ 



U2) = 0.15 mm. 



r, ■ I Lz = 1.00 mm. 

 Zooecia , „ _^ 



1/2 = 0.50 mm. 



Variations. — As on all the giant species, the micrometric variations 



are quite variable. Our measurements are average, as there are 



