310 TJniversity of CaJifornia Publications in Zoology. [Vol. 4 

 79. Retepora pacifica sp. nov. 



PI. 24, fig. 81, 82, 83, 84. 



Zoarimn forming large convoluted masses growing from an 

 incrnsting disk, often with a short peduncle (pi. 24, fig. 81). 

 Fenestra} oval, about twice as long as wide, on the dorsal surface 

 a much elevated avicularium (fig. 82, d. av.) at the base of each 

 fenestra, its mandible directed obliquely downward. Zooecia 

 (fig. 83) small, alternate, front wall granular, sloping upward 

 from the sides to the median line. At the growing tip, the young 

 zooecia (fig. 84), elongate, orifice semicircular on the upper mar- 

 gin, with a notch or sinus on the lower. At each side of the ori- 

 fice two long spines, front wall hyaline. In older stages a high ^ 

 peristome (fig. 83, per.), with a well defined sinus, below which 4 

 on most of the older zoa?cia there develops a much elevated avi- 

 cularium with pointed mandible directed obliquely downward. 

 Ooecia small relatively, set far back, united with the zooecia only 

 secondarily by the growth of the peristome and perhaps the 

 growth downward of the sides of the ocecium ; front wall extreme- 

 ly delicate, usually possessing a distinct denticle, cl., on its oral 

 border, curving inward; rarely a spine projecting on each side 

 in front of the ooecium. 



Eetepora pacifica bears considerable resemblance to E. ^Yal- 

 lichiana, but differs in some important respects from the descrip- 

 tion and draAving of that species as furnished by Hincks (77). 

 B. WaUicJiiana has a rather low peristome and a minute central 

 sinus, while the present species possesses a high, thin peristome 

 with a Avell marked sinus. The dorsal avicularia in R. Wallicli- 

 iana are small, immersed, with mandible directed transversely, 

 those of B. pacifica (fig. 82) are raised, large, its mandible having 

 a distinct downward trend. The shape of the fenestra? is quite 

 different in the two species, those of the present species being 

 twice as long as wide, while those of the specimen of B. Wallich- 

 iana examined are nnich more elongated, being five or six times 

 as long as wide. Furthermore, no mention is made of spines on 

 any of the zoa?cia of B. Wallichiana and they are always readily 

 seen at the young tips of the branches of B. pacifica. 



The frontal avicularia of B. pacifica are not developed on the 





