NO. 2 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 513 



Family Myriozoidae Smitt, 1867 



"The frontal is thick and bears a tremocyst with tubules. Uniporous 

 septulae or dietellae are present. The avicularia are adventitious and 

 bear a pivot. The ovicell is hyperstomial not adjacent to the zooecium 

 and lodged in a niche-like depression of the distal zooecium." (Canu 

 and Bassler, 1923:185.) 



There are two genera, Myriozoum which has tall, branched zoaria, 

 and Myriozoella which is encrusting. 



Genus MYRIOZOUM Donati, 1750 



The zoarium is erect from a small encrusting base, cylindrical and 

 irregularly branched without articulations. The ovicells are usually 

 completely embedded except on younger zooecia. Genotype, Millepora 

 truncata VdiWas, 1766. 



Key to Species of Myriozoum 



1. Avicularium large, nearly as large as the aperture and immedi- 



ately above it, often wanting coarctatum 



Avicularium very small 2 



2. Aperture longer than broad ; avicularia single, situated slightly at 



one side of the midline subgracile 



Aperture round ; avicularia paired, or single, situated opposite the 

 distal border of the aperture ; zoarium more slender .... tenue 



Myriozoum coarctatum (M. Sars), 1850 

 Plate 64, figs. 5-6 



Cellepora coarctata M. Sars, 1850:148. 



Leieschara coarctata, M. Sars, 1862 :155. 



Myriozoum coarctatum. Waters, 1900 :68. 



Myriozoum coarctatum, Hincks, 1884:21. 



Myriozoum coarctatum, Robertson, 1908:295. 



"iMyriozoum coarctatum, O'Donoghue, 1923:38; 1926:76. 



Zoarium irregularly branching to a height of 75 to 100 mm, cylin- 

 drical. Zooecia moderate, about 0.65 mm long, indistinct as there are no 

 lines of separation; the frontal a very thick tremocyst with large pores 

 and no other frontal characters. The aperture is usually a little longer 

 than wide, rounded distally, straighter on the sides, the proximal 

 border transverse with a narrow U-shaped sinus. The primary peristome 



