66 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



A small avicularium, with some areolations about the base of the 

 chamber, situated on the gymnocyst just proximal to the opesia, the 

 mandible usually triangular but occasionally rounded; in the presence 

 of an ovicell the avicularium becomes much larger, elongated and its 

 chamber unites with the distal surface of the ectooecium. 



The ovicell is prominent, rounded, the usual transverse rib present 

 but reduced in size and there are fine longitudinal striae on the other- 

 wise smooth surface. The ovicell, with the distal avicularium, resembles 

 that of the Tegella species. 



This species has recently been placed by Brown in his new genus 

 Retevirgula, on the basis of disjunct zooecia with connecting tubules. 

 That, however, appears to be the only character in common with that 

 genus. Among the numerous colonies at my disposal I have found no 

 zooeciules, though the avicularian chambers sometimes suggest that na- 

 ture ; they are very definitely frontal avicularia developed on the surface 

 of the gymnocyst, and the tubules which appear to connect with them 

 really are connected with the zooecium below the bases of the avicularian 

 chambers. The ovicells of circumclathrata are not like those of Rete- 

 virgula as they lack the fenestra in the ectooecium; they have a fairly 

 close resemblance to those of Tegella, but the presence of large dietellae 

 removes them from that genus. 



Hincks described the species from "Santa Cruz, California," Robert- 

 son listed it from "various localities near the coast of southern Cali- 

 fornia," and O'Donoghue recorded it from numerous localities in British 

 Columbia. 



Hancock Station 1410-41, Santa Barbara Island, California, 20 fms. 

 Numerous specimens from Del Monte, California, 25 feet, (in Miss 

 Blagg's collection) ; also in shallow water at Palos Verdes, Redondo 

 Beach and Santa Monica, California. Pleistocene of Santa Monica Can- 

 yon, California (Canu and Bassler). There is also a specimen labelled 

 merely "off Colombia" ; the datum is probably correct as all of the other 

 species in the lot are definitely tropical. 



Callopora corniculifera (Hincks), 1884 

 Plate 7, fig. 1 



Membranipora corniculifera Hincks, 1884 ;11. 

 ?Caulorampkus triangularis Canu and Bassler, 1923 :48. 



Zoarium encrusting. Zooecia moderately large, 0.60 to 0.70 mm long 

 by 0.40 to 0.50 mm wide, distinct with broad separating grooves ; gymno- 

 cyst usually small but occasionally as much as one-third of the zooecial 



