258 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Occurrence — Continued. 



D. 5162. Tinagta Island, Tawi Tawi Group; 5° 10' N.; 119° 



47' 30" E.; 230 fathoms; brk. Sh. crs.; 11.6° C. 

 D. 5577. Mount Dromedario, Tawi Tawi; 5° 20' 36" N.; 119° 



58' 51" E.; 240 fathoms; crs. S.; 12.4° C. 

 D. 5579. Sibutu Island, Darvel Bay, Borneo; 4° 54' 15" N.; 



119° 09' 52" E.; 175 fathoms; fine S., co.; 13° C. 

 D. 5580. Sibutu Island, Darvel Bay, Borneo; 4° 52' 45" N.J 

 119° 06' 45" E.; 162 fathoms; br. S., co.; 13.2° C. 

 Cotypes.— Cat. Nos. 8000, 8001, U.S.N.M. 



PETRALIELLA GIGANTEA, new species 



Plate 23, figs. 10, 11 



Description. — The zoarium is unilamellar. The zooecia are dis- 

 tinct, separated by a deep furrow, very large, elongated, elliptical; 

 the frontal is convex and covered by large tremopores; the shield is 

 bipartite distally, cushionlike laterally, and bears a dissymetric 

 avicularian umbo before the aperture. The aperture is very large, 

 semicircular, and provided with two small cardelles, one of which is 

 always more salient than the other; the peristome is very thin and 

 often little visible. The ovicell is buried in the distal zooecium, 

 covered with an olocyst. Sometimes small sporadic avicularia appear 

 either on the shield or in its vicinity. On the interior face each 

 zooecium bears a large distal perforated area. 



Measurements. — 



. \ha -0.31-0.40 mm. „ . \Lz -1.75-2.25 mm. 



Aperture 7 Zooecia 7 , n _ 



I to «=0.45-0.50 mm. Uz =1.00 mm. 



Variations. — As on all the giant species, the micrometric measure- 

 ments are variable and there are some small cells at the side of the 

 very large ones. The small avicularia are very inconstant in position 

 and in frequency. Our specimens were dead. The cells are visible 

 to the naked eye. 



Biology. — This is a species of great depths. 

 Occurrence. — 



D. 5162. Tinagta Island, Sulu Archipelago; 5° 10' N.J 119° 



47' 30" E.; 230 fathoms; S. brk., Sh. crs. 

 D. 5579. Sibutu Island, Darvel Bay, Borneo; 4° 54' 15" N.J 

 119° 09' 52" E.; 175 fathoms; fine S., co. 

 Cotypes.— Cut. Nos. 8014, 8015, U.S.N.M. 



PETRALIELLA GRANDICELLA, new species 



Plate 24, figs. 1-4 



Description. — The zoarium is unilamellar. The zooecia are dis- 

 tinct, separated by a very deep furrow, large, elongated, elliptical; 

 the frontal is very convex and covered with granules and with large 

 widened tremopores; an enormous bifid avicularian umbo hides almost 



