38 PROCEEDINGS OF THE NATIONAL MUSEUM vol.76 



oral avicularium and a projection of the peristome and that its plane 

 is oblique to the plane of the apertura. 



The colonies are very often adorned with marginal oriented cells 

 They are never visible on floating specimens. 



The operculum is in the form of a bell with the two lateral bands 

 near the border. 



Affinities. — All of the affinities of this species are with Cellepora 

 hispinosa Busk, 1852, from Australia; the same frontal, ovicell, 

 oriented cells, and the same pseudorimule in front of the apertura. 

 Busk, 1852, figures two spines on the marginal zooecia ; MacGillivray 

 did not figure them, l)ut indicates two large articulated spines on the 

 cumulate zooecia. 



If the operculum figured by us had been identical with that of 

 MacGillivray, we would not have created a new species; the position 

 of four spines on the oriented zooecia and the two on the cumulate 

 zooecia indicated only varietal characters. MacGillivray's figure is 

 so abnormal in the genus that it is perhaps erroneous. 



Biology. — The ectocyst is white. Some rare living specimens were 

 ovicelled April 7 to 9, 1888. 



The specimens incrusting shells appear to have lived on the bottom 

 where dredged, but a certain number of other specimens are at- 

 tached to filaments of algae ; they are cylindrical or similar to our 

 Figure 4. Colonies developed on both sides of a fragment of shell 

 or surrounding entirely a piece of coral are also subfloating. By 

 floating specimens we do not intend to imply that they float freely 

 as Gupularia or C onescharelUna'., we mean only that they are devel- 

 oped on or attached to floating bodies and that they have no bathy- 

 metric significance. There were often mollusks attached to the tufts 

 of marine algae, and it is these which these organisms like the Celle- 

 pores entirely surrounded. 



Holoporella quadrispinosa is therefore a species both fixed and 

 floating. 



Occurrence. — Galapagos Islands, D. 2813 and D. 2815. 



C otyp^s.— C2ii. Nos. 8511, 8512, U.S.N.M. 



HOLOPORELLA HEXAGONALIS, new species 



Plate 7, Figure 1 



Description. — The zoarium incrusts debris of shells. The zooecia 

 are distinct, separated by a furrow, rather regularly hexagonal, non- 

 oriented; the frontal is convex and covered with scattered pores. 

 The apertura is semielliptic or suborbicular, median ; it is surrounded 

 by four salient avicularian tuberosities. 



Measurements. — Apertura, Za=0.20 mm. Zooecium, 7s=0.50- 

 0.65 mm. 



