NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 377 



9. Ascopore large with cribrate aperture (sieve plate) . . cribrosa 



Ascopore with the usual lunate aperture californica 



10. Avicularia small, a small setose mandible setiformis 



Avicularia with narrow hastate mandible ending in a setose 

 point coronata 



Microporella ciliata (Pallas), 1766 

 Plate 44, fig. 1 



Eschara ciliata van B Pallas, 1766 :38. 



Cellepora ciliata, Linnaeus, 1759 : 1286. 



Microporella ciliata, Hincks, 1880:206; 1884:14. 



Microporella ciliata, O'Donoghue, 1823 :31 ; 1925 :103 ; 1926:64. 



Microporella ciliata, Canu and Bassler, 1923 :1 19. 



Microporella ciliata, Hastings, 1930:727. 



Zoarium encrusting on various substrata, especially shells and stones. 

 The zooecia are somewhat ovate to elongate hexagonal; (length 0.45 to 

 0.50, width 0.30) ; the front with numerous small tremopores, shghtly 

 inflated, smooth and usually without decoration, though a small median 

 umbonate process is sometimes present. The aperture is nearly semi- 

 circular, evenly rounded in front and on the sides and straight on the 

 proximal border; 0.08 or 0.09 mm long by 0.11 to 0.13 mm wide; 

 the peristome low and smooth with 5 to 7 oral spines. The ascopore, 

 in the midline a little proximal to the aperture, is lunate (a small 

 calcified shelf projects backward from the distal border of the pore 

 partially closing the pore). 



The ovicell is globose and prominent, smooth or umbonated on the 

 top and ribbed around the base; a slight collar around the aperture; 

 about 0.25 mm in width. 



Usually there is a single avicularium situated a little to one side of 

 the midline and proximal to the ascopore, the mandible long triangular 

 to more or less setose directed forward and outward. Occasionally there 

 are two avicularia s>Tnmetrically placed, and the location may vary from 

 the lateral zooecial angle to opposite the ascopore. 



A cosmopolitan species, listed on the American Pacific coast by Hincks 

 and O'Donoghue from British Columbia waters and by Hastings from 

 Panama, Colombia and the Galapagos Islands. 



In the Hancock collections it appeared at nearly 100 stations from 

 the coast of Oregon to the Galapagos Islands, from near shore to depth 

 of 90 fathoms. 



