NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 501 



Strong spines which are usually flattened and oar-shaped (occasionally 

 cylindrical) and jointed at the base. Proximal to the aperture is the usual 

 avicularian umbo, typically small and low, but on marginal zooecia may 

 be much larger; the avicularium situated usually at one side of the 

 rostrum with the short spatulate mandible (0.08 mm long by 0.06 mm 

 wide) directed upward, the beak dentate. The interzooecial avicularia 

 are rare, not elevated, long-oval in form and ranging in length from 

 0.15 to 0.40 mm long, the mandible without a complete pivot. The 

 primary aperture is slightly more than a semicircle and the proximal 

 border a broad arc with a shallow notch at its middle, width about 0.18, 

 the length 0.15 mm. The operculum is light brown, thin, with a strong 

 dark brown sclerite on each side, running diagonally forward from the 

 point of attachment. 



The ovicell is characteristic of the genus, a wide-open hood, imper- 

 forate, granulated like the frontal, prominent and measures 0.25 to 

 0.30 mm in width. 



The species appears to have much in common with H. pilaefera Canu 

 and Bassler (1930:422) from the Philippines, and if I am not mistaken 

 in my interpretation of their figure (plate 60, figs. 4 and 5) the "enor- 

 mous cylindrical beak, in the form of a pillar" is of the same nature 

 as the similar appearing one in the present species, as its distribution 

 appears to be interzooecial. Their figures show the tube to be closed 

 at the tip and this is true also of a few of the tubes in peristomata. The 

 nature of the tube seems definite enough as the dissection of some of the 

 shorter ones near the margin revealed an operculum at the bottom. 

 The exposed tubes are thick-walled and their apertures perfectly cir- 

 cular, their buried bases descend to different levels indicating that 

 they are from lower layers. The tubes are merely the projected peristomes 

 of zooecia of the lower layers. 



The present species differs from pilaefera in the form of the inter- 

 zooecial avicularia, the presence of distal oral spines and in the nature of 

 the ovicell which is much less complete and much smoother in texture. 



Type, AH F no. 111. 



Type locality, Hancock Station 346-35, between South Seymour and 

 Daphne Islands, Galapagos, 0°24'25"S, 90°21'50"W, 55 fms, one 

 colony. Also 4 young colonies from Sta. 182-34, off James Bay, James 

 Island, Galapagos, 30 fms; and 324-35, Tagus Cove, Albemarle Island, 

 Galapagos, 45 fms. 



