1^08] Robertson. — Incrusting Bryozoa. 311 



latei-al zooecia of the trabecuhv. They are high, i.e., they project 

 from the front of the zoo'cia and when viewed in profile resemble 

 the avicularia of the Bicellariida'. A fine specimen taken at low 

 tide at La Jolla was a deep orange in life. It differs from speci- 

 mens obtained at higher latitudes mainly in its greater delicacy 

 and in the smaller size of the fenestras and of the zooecia. The 

 ocpcial wall is extremely thin and the denticle is not always ap- 

 parent, there being rather a mere tendency to dip downward or 

 slightly inward on the middle of the oral rim. 



This species has a wide distribution on the western coast, 

 being found in Puget Sound, San Juan Co., Washington, and at 

 various points on the California coast between tide marks, and 

 dredged from depths of 20 to 30 fathoms. 



80. Retepora pacifica catalinensis subsp. nov. 



PI. 24, figs. 85, 86. 



Dredged on the west coast of the island of Santa Catalina is 

 a quantity of what is considered a variant of Retepora pacifica. 

 The zooecia are smaller than those of the type, but the chief dif- 

 ferences lie in the greater height of the peristome and in the loop 

 formed by the peristome in front. The youngest zooecia at the 

 growing tip cannot be distinguished from those of R. pacifica (pi. 

 24, fig. 84). At an early stage, however, the peristome elevates, 

 especially in front, so that in a zooecium that has not acquired an 

 ovicell the secondary orifice is almost quadrangular (fig. 85), and 

 instead of a sinus such as appears in R. pacifica, a pore, p., is 

 formed by the union of the inner edges of a loop of the peristome, 

 which had they remained apart would have formed a sinus sim- 

 ilar to that in R. pacifica. In still older zooecia (fig. 86), the 

 peristome rises still higher into two broad points or plates, pi., 

 which thus form a sinus above the pore. In this stage an avicul- 

 arium is developed on the front wall of each zooecium, and an 

 ovicell with a well developed mucro appears. The ooecium, like 

 that of the typical R. pacifica, is set far back and thus changes 

 the apparent shape of the secondary orifice. The primary orifice 

 in the sub-species is wholly invisible when the secondary orifice is 

 formed, whereas in R. pacifica it (fig. 83, pri. or.) may be par- 

 tially seen even in the oldest stage of growth. 



