498 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



resembling a conical spine; the suboral avicularium is situated near the 

 base of the umbo, with the spine towering high above it; the spines 

 of lower layers often project between the zooecia of the layers above. 

 The frontal is ventricose, smooth or granular, with a single row of 

 rather small areolar pores. The aperture is a little more than a semi- 

 circle, the proximal border broadly arcuate, the operculum thin and 

 colorless with narrow linear sclerites close to the border. The inter- 

 zooecial avicularia are of two kinds, long (0.40 mm or more) with 

 a spatulate mandible, and shorter (about 0.25 mm) with a narrower 

 mandible. 



Ovicell a wide open hood. 



Older colonies with the dark pigmentation of the ectocyst and with 

 the white tips of the spines are easy of identification, but younger 

 specimens usually lack the color and there is considerable variation in 

 the size of the spinous processes. 



Smitt described the species from Florida and it is a common species 

 in the Gulf of Mexico and the Caribbean Sea (Osburn and Canu and 

 Bassler). It has been recorded from the Indian Ocean and from Aus- 

 tralia; in the Miocene of Jamaica and Australia, and the Pliocene of 

 Florida and New Zealand. 



Hancock Station 788-38, Daphne Major Island, Galapagos. 



Holoporella tridenticulata (Busk), 1884 

 Plate 61, fig. 7 



Cellepora tridenticulata Busk, 1884 : 198, 



Holoporella tridenticulata, Canu and Bassler, 1929:39. 



Encrusting on algae and corallines and there are two colonies on a 

 small pebble ; small, rough surfaced and multilaminar. The zooecia are 

 erect or nearly so, except at the margin of young colonies where they 

 measure 0.60 to 0.70 mm long by 0.40 to 0.50 mm wide. The frontal 

 in marginal individuals is inflated, smooth and imperforate except for a 

 few small areolar pores; rising on all sides to the level of the primary 

 aperture which is horizontal. The peristome is but little elevated above 

 the operculum and proximal to the aperture there is a small, low avicu- 

 larian umbo, the mandible semicircular and directed upward on the 

 distal side. The primary aperture rounded distally, nearly transverse 

 on the proximal border where there are three denticles (the middle one 

 larger and sometimes divided into two) ; the operculum delicate with 

 a brown bordering sclerite. The peristome bears 2 to 4 erect spines, 



