260 University of California Puhlications in Zoology. [Vol.4 



some of which are of great length, the two most distal frequently 

 equaling that of a zooecium. 



This species is reported by Hincks from Santa Cruz, Califor- 

 nia. Obtained in dredgings from various localities near the coast 

 of southern California. 



37. Membranipora horrida Hincks. 



PI. 14, fig. 3, 4. 



Membranipora horrida Hincks, 1880a, vol. 6, p. 82, pi. 10, fig. 6. 

 ^Membranipora californiensis Waters, 1898, p. 681, pi. 49, fig. 14. 



Zoaria forming brittle masses incrusting shells, sponge, and 

 other bryozoa. Zooecia ovate, more or less distant, alternate (pi. 

 14, fig. 3) ; aperture, sometimes oval, sometimes almost circular, 

 and closed by a membranous wall ; margin raised, thickened, and 

 slightly erenate; on young zooecia, or on those in protected por- 

 tions of the colony, four or six long, stout sj^ines on the upper 

 half of the margin ; on the lower half and springing" from the 

 outer edge are frequently four, but sometimes six delicate spines 

 overlapping' the front wall l)ut not meeting'. Immediately below 

 the aperture and somewhat to one side of the median line, is a 

 slightly elevated avicularium with long tapering mandible di- 

 rected obliquely either toward the right or left, sometimes curv- 

 ing slightly around the margin of the aperture ; sometimes a 

 second smaller aviculariuni appears below the aperture with 

 mandible pointing in a direction opposite to that of the other. 

 Occasionally a few very large avicnlaria are fouiid (fig. 4) which 

 in size are equal to about half that of an ordinary zooecium, the 

 lower portion, zoe., representing the part of the zorocium occupied 

 by the polypide, the upper portion, op., representing the oper- 

 culum and forming' the mandible of the avicularium, the whole 

 surrounded by a calcareous margin similar to that surrounding 

 the zoa?cia ; mandible broad and rounded at the tip ; directed 

 distally. Ooecia (fig. 3, oc.) small, rounded, smooth, a rib across 

 the front a little above the oral rim ; sub-innnersed, the avicular- 

 ium which is ordinarily below the aperture resting partly upon 

 the ooecium. 



Much variation, especially in the number of the spines and in 



