380 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Hancock Stations: 1232-41, San Pedro; 1171-40, 1371-41 and 1118, 

 off Santa Catalina Island; 1051, San Miguel Island, and 1153, Santa 

 Rosa Island, all from southern California. Stations 488-36, San Quentin 

 Bay; 1250-41, San Benito Island, and 1261-41, Dewey Channel, all 

 from Lower California, west coast. 5 to 160 fms. Also at Middle Bank, 

 Puget Sound, Washington, Dr. J. L. Mohr, collector. These records 

 extend the range from British Columbia to about the parallel 28°N Lat. 



Microporella cribrosa new species 

 Plate 44, fig. 3 



Microporella californica Robertson, 1908:281 (non Busk). 



There is much general zoarial resemblance to californica Busk, but 

 differences occur in several characters. The most evident of these is the 

 presence of a perforated cover, "sieve plate" (Robertson), over the asco- 

 pore, instead of the usual lunate opening. The zoarium usually encrusts 

 algae, but sometimes is found on shells and pebbles. The zooecia resemble 

 those of californica but average smaller, about 52 mm long by 0.35 mm 

 wide. The tremopores are large and there is often a small umbonate 

 process proximal to the ascopore: the process rarely becomes high and 

 flabellate. The aperture is more transverse than usual in this genus, 

 nearly twice as wide as long, 0.07 to 0.08 long by 0.13 to 0.15 mm wide, 

 straight on the proximal border, the small cardelles usually evident. 

 The ascopore is larger than in any other of our species, transversely 

 short-elliptical, often a little inflected on the distal border where a small 

 projection may extend a short distance into the aperture ; the remainder 

 of the aperture of the ascopore is filled in with a calcified, porous mem- 

 brane, the numerous pores perfectly round (Robertson's figure represents 

 this feature well). 



The avicularia are similar in form and position to those of cali- 

 fornica but smaller. The spines, usually 6 (5 to 7), are long, sometimes 

 longer than a zooecium, and strong, jointed at the base and occasionally 

 dark about the basal joint. 



The ovicells are larger than those of californica (though the zooecia 

 are smaller), averaging 0.35 mm in width (0.33 to 0.38 mm), the base 

 of young undeveloped ones measuring 0.28 mm in width. As in most 

 species of the genus they are ribbed about the base, but the base is rather 

 sharply constricted. A low smooth umbo is present on the top and the 

 sides extend backward to the proximal spines. 



