NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA — CHEILOSTOMATA 29 



Membranipora hastingsae new species 

 Plate 2, fig. 1 



Acanthodesia serrata, Hastings, 1930:707. 



Zoarium encrusting. The zooecia are moderate in size, elongate and 

 quite regularly quandrangular in form; walls very thin. The most 

 characteristic feature is the very extensive development of the cryptocyst, 

 which extends broadly on the sides to the level of the operculum, with 

 numerous elongate spinules, rather evenly spaced, which nearly meet 

 across the opesia and which occur on the entire lateral cryptocyst as far 

 as to the operculum. The polypide chamber is thus almost enclosed 

 beneath the cryptocyst and its horizontal spinules. At each corner there 

 is a triangular area which appears to occupy all of the g^^mnocyst and 

 which develops into a nodule, according to Hastings, or a short spine. 



Dr. Hastings has described incipient avicularia of the same size as 

 the zooecia and possessing a polypide, but with a greatly enlarged and 

 somewhat modified operculum. The small specimen in my possession 

 does not show the avicularia, but otherwise the agreement with her de- 

 scription and excellent figures (Plate 4, figs. 13-15) is perfect. 



Dr. Hastings was evidently in error in listing this form under the 

 serrata of Hincks for the following reasons: (1) the cryptocyst is re- 

 markably broad and evenly developed on the sides and extends to the 

 distal wall, where it leaves only space for the operculum (in serrata the 

 cryptocyst is always narrow) ; (2) the spinules are long, extending nearly 

 or quite to the median line, very equally developed and evenly spaced to 

 the opercular area (in serrata the edge of the cr>^ptocyst is crenate, with 

 occasional shorter denticles irregularly distributed) ; (3) the spines at 

 the corners are much less developed than in serrata. Furthermore I have 

 examined large numbers of serrata and found no evidence of "incipient 

 avicularia." 



It is a pleasure to name this species for Dr. Anna B. Hastings of the 

 British Museum of Natural History, who has done so much to further 

 our knowledge of the Bryozoa. 



The type material consists of a single colony from Balboa, Canal 

 Zone, sent to me for identification by the William F. Clapp Laboratories 

 of Duxbury, Massachusetts. Dr. Hastings recorded it as Acanthodesia 

 serrata, also from Balboa "docks, buoy and shore." 



Type, AHF no. 11. 



Type locality, Balboa, Canal Zone. Also from Perlas Islands, Gulf 

 of Panama, F. H. Bradley, collector. 



