316 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



The rimule of the apertura is often separated from the apertura 

 and represented simply by a small pore; but the proximal tongue of 

 the operculum is quite constant. 



Biology. — This species was in reproduction and fixation in Feb- 

 ruary and March, 1908 (37-67 meters). Our specimens from Tacbuc, 

 collected in July were ovicelled but as they were dead we can not be 

 sure that their reproduction continued until them. This is a species 

 of shallow water, living by preference in the channels and numerous 

 straits of the Philippine Islands. Its geographic distribution in the 

 region is great, but it is always rare. 

 Occurrence. — 



D. 5137. Jolo Light, Jolo; 6° 04' 25" N.; 120° 58' 30" E.; 20 



fathoms; S. Sh. 

 D. 5141. Jolo Light, Jolo; 6° 09' N.; 120° 58' E.; 29 fathoms; 



co. S. 

 D. 5144. Jolo Light, Jolo; 6° 05' 50" N.; 121° 02' 15" E.; 



19 fathoms; co. S. 

 D. 5147. Sulade Island, Sulu Archipelago; 5° 41' 40" N.; 120° 



47' 10" E.; 21 fathoms; co. S., Sh. 

 D. 5151. Sirun Island, Tawi Tawi Group; 5° 24' 40" N.j 120° 



27' 15" E.; 24 fathoms; S. Sh. 

 D. 5179. Romblon Light, Romblon; 12° 38' 15" N.; 122° 12' 



30" E.; 37 fathoms; hard S.; 24.2° C. 

 D. 5478. Tacbuc Point, Leyte; 10° 46' 24" N.; 125° 16' 30" 

 E.; 57 fathoms; Sh. 

 Cotypes.— Cat. Nos. 8073-8075, U.S.N. M. 



STYLOPOMA GRANDIS, new species 



Plate 37, figs. 1-3 



Description. — The zoarium encrusts shells (Tridacna) in pluri- 

 lam ell ar masses. The zooecia are large, distinct, separated by a deep 

 furrow, arranged in every direction without apparent order; the 

 frontal is convex and perforated by large expanded tremopores and 

 bears on each side of the rimule of the apertura a small triangular 

 oblique avicularium with a very pointed and salient beak. The 

 apertura is large, transverse; the anter is semielliptical ; the proximal 

 border is straight and notched by a broad shallow, rounded rimule. 

 The ovicell is enormous (0.75 mm. in diameter), porous and entirely 

 covers the apertura and its avicularia. The large interzooecial avicu- 

 laria are modified zooecia. They have a pivot and a long very pointed 

 canal. • 



Measurements. — 



k = 0.20mm. n \Lz = 0.75-1.00 mm. 



A , f/ia = 0.20 mm. n 



Apertura^ * Zooecia 



v \la = 0.22 mm. 



lz = 0.50-0.75 mm. 



