264 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Affinities. — In its zooecial aspect this species is close to Petraliella 

 philippinensis; it differs from it in its much smaller micrometric 

 measurements and in the absence of a large spatulate avicularium. 

 It differs also from Petraliella armata in its much smaller lyrula, in 

 the absence of a large avicularium and in the presence of a larger 

 number of small adventitious avicularia. The operculum is not 

 very distinctly separated from the compensatrix. 



Biology. — All of our specimens were dead. This is a species of 

 great depths. The specimen from Tacbuc (103 meters) the locality 

 of least depth, was most highly ornamented. 

 Occurrence. — 



D. 5162. Tinagta Island;. 5° 10' N.; 119° 47' 30" E.; 230 



fathoms; S. brk., Sh. crs.; 11.6° C. 

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



57 fathoms; Sh. 

 D. 5574. Simaluc Island, north of Tawi Tawi Group; 5° 30' 



45" N.; 120° 07' 57" E.; 340 fathoms. 

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



58' 51" E.; 240 fathoms; crs. S. 

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

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

 Cotypes— Cat. Nos. 8012, 8013, U.S.N.M. 



PETRALIELLA TUBULIFERA, new species 



Plate 27, figs. 7-12 



Description. — The zoarium is unilamellar or incrusting; it is a very 

 clear rose brown with the opercula colored yellow. The zooecia 

 are distinct, separated by a furrow, elongated, elliptical; the frontal 

 is convex and covered with widened, crowded tremopores; the shield 

 is much ornamented and bears distally 3-6 large hollow spines, 

 laterally 2 small salient avicularia and before the aperture an enor- 

 mous avicularian mucro bifurcated or branching, adorned with very 

 salient tubules. The aperture is semielliptical transverse; the 

 proximal border bears two indentations separating a small lyrula 

 from two large triangular cardelles. The ovicell is hyperstomial 

 and formed of an olocyst covered by a tremocyst with very fine 

 pores. The inferior face is deprived of radicular pores. 



Measure ments. — 



fk=0.15 mm. „ . [1,2=0.60 mm. 



Aperture]^ =0 2Q _ 23 mm Zooecia^ =Q UQ 4Q mm 



Variations. — We have observed some specimens encrusting nulli- 

 pores; they were ancestrulated. Like all the species with intense 

 calcification the exterior variations are considerable; there is not a 

 single cell exactly similar to its neighbor nor one lamella like another; 

 the decoration of the shield varies according to the needs of the 

 animal as shown in our photographs chosen from more extreme 



