ir ^ A ^ ^a = 0.14-0.16 



Measurements. — Apertures ^ ^ , ^ ^ , „ 



^ lia = 0.16-0.18 



148 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.72 



HOLOPOEELLA VAGANS Busk, 1885 



Plate 25, Figures 7-13; text Figure 33 e-g 



1885. Cellepora vagans Busk, Polyzoa of Challenger, Report Results Voy- 

 age Challenger, vol. 10, pt. 30, p. 198, pi. 29, fig. 10; pi. 35, fig.ll. 



f^a = 0.14-0.16 mm. 



iZa = 0.16-0.18 mm. 



Length of avicularia = 0.30-0.50 mm. 



Variations. — The characters of our specimens are in perfect accord 

 with those Busk has given for his Cellepora vagans. The oral sinus 

 is very small although the rimule of the operculum is very large 

 The zooecia are surrounded by areolar pores. The small oral avicu- 

 arium has a very salient beak. The marginal or ancestrular cella 

 are oriented. Finally the interzooecial avicularia are long, rather 

 thin with generally a linear mandible. 



Busk gave only a small figure and spoke little of the variations » 

 Here the small specimens are orbicular. The largest are unilamellar 

 and free, or perhaps they form small rods, increasing cylindrically 

 without base of fixation. The interzooecial avicularia are a little 

 enlarged at their beak and their mandible is somewhat spatulate. 



On the massive and tuberose colonies the tuberosities are formed 

 by groups of large zooecia. Between these tuberosities there are 

 groups of small zooecia in which the orifice measures only 0.10 by 

 0.14 mm. 



None of our specimens were ovicelled. The operculum does not 

 correspond to the form of the aperture. In spite of the apertural 

 proximal sinus, the operculum shows the essential characters of Holo- 

 porella. In view of this anomaly, we have made many preparations 

 of specimens from different localities and all the opercula had the 

 characteristic form of Holoporella with the two lateral bands. 



Affinities. — In the form of the interzooecial avicularia this species 

 is very close to Holoporella alhirostris Smitt, 1873. It differs from 

 it in the presence of a small proximal sinus with aperture and in the 

 absence of a large avicularian umbo. 



Biology. — The colonies have a beautiful flesh color. The larvae 

 fix themselves on small grains of solidified mud. The young colonies 

 form small disks in which the maximum dimension is 10 mm. The 

 older and larger colonies have forms incompatible with their devel- 

 opment on the sea bottom. It is presumed that they escape from 

 the bottom and are able to float with a certain ease. The absence 

 of a base of fixation confirms this hypothesis. This phenomenon is 

 not limited to the present species, but it can be observed on a very 

 large number of massive and free species. It is necessary then ta 

 conclude that all the Cellepores have been floating colonies and that 

 this is the principal cause for their irregular development. Their 

 extreme lightness in dry condition is well known. 



