266 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Zooecia 



Lz= 1.10 mm. 



Measurements. — 

 . ]7i,a = 0.24 mm. 



Aperture j^ = QZQ mm MMV% ^ m \U = 0.70 mm. 



Affinities. — The spinous aspect of this species is very characteristic; 

 each colony is truly a small forest of spines. The species differs from 

 Petraliella tubulifera in the presence of spines on the frontal, in its 

 smaller cardelles and in the larger dimensions. Its aspect is still more 

 fantastic. 



Biology. — The zoarium is sometimes greenish, sometimes of a superb 

 clear rose; it is the ectocyst which is thus colored. It is difficult to 



Fig. 107. — A-C. Petraliella echinata, new species 



A. Oral spines, X85, of olocystal structure. B. Operculum, X85, with mar- 

 ginal band much chitinized. C. Usual form, X85. D, E. Petraliella verrucosa, 

 new species. D. Operculum, X85, showing point of attachment of occlusor 

 muscles. E. Another operculum, X85. 



understand the difference in pigmentation as two small colonies on the 

 same nullipore may have different colors. 



The operculum is white; it see saws on the transverse axis of the 

 aperture without any apparent lateral support; the lyrula and the 

 cardelles serve only to stop the movement of the operculum when it 

 becomes closed. 



Our specimens were living. The species was in full reproduction 

 and fixation February 1, 1908 (34-52 meters). It does not occur at 

 the same localities as Petraliella tubulifera and contrary to this species, 

 it preserves all its ornamentation in slight depths of water. 

 Occurrence. — 



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. 

 Cotypes.— Cat. Nos. 8020, 8021, U.S.N.M. 



