88 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



This species differs from R. lata in the looser connection of the zo- 

 oecia, the smaller size, the narrower opesia, the position of the ooecial 

 fenestra and especially by the extensive development of the spines. 



This species was described from the Pleistocene of Santa Monica, 

 California, by Canu and Bassler, who were uncertain as to its generic re- 

 lationships. The ovicell and avicularium are lacking in their material, 

 but the other characters correspond fairly well. 



Hancock Stations 1283-41, off Santa Rosa Island, California, 28 fms, 

 10 colonies on large coralline; Redondo Beach, California, shallow water; 

 Point Vicente, California, 14 fms. Also Monterey Bay, California (Blagg 

 collection). 



Family Ghapperiidae Bassler, 1935 



Represented by the one genus, Chapperia. Usually this genus has been 

 associated with other membraniporine forms in the Anasca, but Canu and 

 Bassler (1927) separated it widely and placed it under their new sub- 

 order Hexapogona on what appears to be a very insufficient character, 

 viz. "The ancestrula engenders six zooecia." It is true that the usual 

 number of buds on the cheilostome ancestrula is five, but the number 

 varies all the way from one to six among the encrusting species, and also 

 varies somewhat within a single species. I have noted as few as four in 

 one colony of Chapperia patula (Hincks), and six are occasionally found 

 in other anascan species. 



The most unusual character of the group is the presence of "occlusor- 

 laminae" (Harmer), a pair of horizontal projections arising from the 

 lateral walls opposite the operculum and considerably beneath it. They 

 afford attachment for the occlusor muscles of the large operculum ; 

 there is much variation in size and in some species they are scarcely 

 noticeable, often obscured by the lateral cryptocyst above them ; at their 

 fullest development they may unite to form a continuous shelf around 

 the distal end. Spines, simple, forked or cervicorn, are present on all of 

 our species. Avicularia may be either sessile or pedunculate, and both types 

 are sometimes present on the same colony. The ovicell is hyperstomial, 

 prominent, cucullate and not closed by the operculum. Large multipor- 

 ous septulae are located rather high in the lateral and distal walls. 



The general characters of this group appear to be anascan and I am 

 therefore returning the Chapperiidae to the Anasca following the Al- 

 derinidae, to which they seem to have the closest affinity. 



