328 BULLETIN 100. UNITED STATES NATIONAL MUSEUM 



bears infundibuliform tremopores, two small special pores and laterally 

 an elliptical avicularium with pivot. The apertufa is buried at the 

 bottom of a deep peristomie. The peristome is thick and orbicular. 

 Measurements. — 



Peristomice.j^ = - 10 mm ' Zooecia(^ = - 50 -°- 75 mm " 



Hp = 0.10-0.12 mm. Us = 0.50 mm. 



Affinities. — This species differs from Didymosella crassa Canu and 

 Bassler, 1920, and from Didymosella porosa Stoliczka, 1864, in its 

 especially small pores. These three species are very close together. 

 Our specimens were dead and very rare. 

 Occurrence. — 



D. 5137. Jolo Light, Jolo; 6° 04' 25" N.J 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. 

 Holotype — Cat. No. 8095, U.S.N.M. 



DIDYMOSELLA COSTULATA, new species 



Plate 39, figs. 2, 3 



Description. — The zoarium is unilamellar. The zooecia are little 

 distinct, somewhat elongated, swollen; the frontal is an olocyst bear- 

 ing a costulated tremocyst; it has the two characteristic pores and 

 laterally an elliptical, transverse avicularium. The apertura is 

 buried at the bottom of an irregular peristomie; the peristome is very 

 thick and bears some spines. The ovicell is deeply embedded in the 

 distal zooecium ; it is formed of an olocyst incompletely covered by a 

 costulated tremocyst. The operculum closes the ovicell. 



Measurements. — 



~ . ± . \7ip = 0.15-0.18 mm. „ . \Lz = 0.70-0.75 mm. 

 Penstomice , . , _ _. , Zooecia , „ _ _ _ _ _ 



I lp = 0.15-0.18 mm. [lz = 0.55-0.65 mm. 



Our specimens were dead and we were not able to make any further 

 observations. 

 Occurrence. — 



D. 5145. Jolo Light, Jolo; 6° 04' 30" N.J 120° 59' 30" E.; 23 



fathoms; co. S., Sh. 

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



120° 47' 10" E.; 21 fathoms; co. S. Sh. 

 P. 5162. Tinagta Island, TawiTawi; 5° 10'N.; 119° 47' 30" E.; 

 230 fathoms; S. brk., Sh. crs.; 11.6° C. 

 Cotypes— Cat. Nos. 8096, 8097, U.S.N.M. 



