152 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



CALLOPORA AURITA Hincks. 1877. 



Plate 29, fig. 2. 



1877. Membranipora aurita HINCKS, On British Polyzoa, Annals and Magazine Natural 



History, ser. 4, vol. 20, p. 213. 



18SO. Membranipora aurita HINCKS, British Marine Polyzoa, p. 159, pi. 21, figs. 5, 6. 

 1894. Membranipora aurita LEVINSEN, Mosdyr. Zoologica Danica, Hefte 9, p. 59, pi. 4. 



figs. 31-38. 

 1902. Membranipora aurita CAI.VET, Bryozoaires des cotes de Corse, Travaux di- 1'Institul 



tie Zoologie de 1'Universite cle MontpelHer, ser. '2, Memoire 12, p. 34. 

 1909. Membranipora aurita LEVINSEX. Morphological and Systematic Studies on the Cheilo- 



stomatous Bryozoa, p. 150. pi. 9, fig. 4. 

 1912. Membranipora aurita OSBURN, The Bryozoa of the Woods Hole Region, Bulletin 



Bureau Fisheries, vol. 30. p. 230, pi. 23, fig. :!7. 



Measurements. Opesia 



ho 0.20-0.25 mm. 

 Zo=0.10 mm. 



Zooecia 



Zs=0.25 mm. 

 Iz 0.17 mm. 



Affinities. Only the single figured specimen has been found and unfortunately 

 it is incomplete. The frontal of the ovicells is destroyed and the avicularia are 

 inconstant. We think, however, that our determination of the species is correct. 

 Our specimen is tubular, as it grew about a small alga at a bifurcation. Concerning 

 this method of growth, Osburn wrote : " Zoarium incrusting, usually on shell, but 

 often on algae ... on the stems of algae the zooecia are generally irregular and 

 the cells sometimes crowded." 



The zooecial micrometric dimensions correspond exactly with those in Levin- 

 sen's figure. The opesial dimensions are very close to those which may be measured 

 on the figure given by Hincks. 



In the vicinity of the two areal spines there is a contraction of the opesium. 

 The same characteristic may be observed in Osburn's figure. 



On many zooecia we have observed small avicularia in the same position as 

 shown in the published figures, but they are not constant. They appear a little 

 larger in the lateral portions of the zoarium. It thus appears very difficult to find 

 any important differences between this fossil form and the recent Membranipora 

 aurita Hincks. 



This species has hitherto never been found in the fossil state, and indeed, it 

 was only recently discovered by Osburn in the West Atlantic. 



Occurrence. Middle Jacksonian( Castle Hayne limestone) : Wilmington. North 

 Carolina (very rare). 



Habitat. North Sea : Off England and Denmark in the English Channel. 

 Mediterranean. Eastern Atlantic : Azore Islands. West Atlantic off the coast of 

 the United States. 



It lives at depths from 5 to 34 meters. However, at the Azores it has been 

 dredged at a depth of 130 meters. 



Plcsiotype.Csit. No. 63!>1!. V'.S.X.M. 



