22 PROCEEDINGS OF THE NATIONAL MUSEUM vol.72 



Genus HINCKSINA Norman, 1903 



HINCKSINA PERIPOROSA, new species 



Plate 2, Figures 8-11 



Description. — The zoarium encrusts bryozoa, corals, nullipores, 

 hydroids, and shells. The zooecia are distinct, separated by a deep 

 furrow, surrounded by a line of inter junctural pores, oval; the gym- 

 nocyst is small, convex; the mural rim is very thin and bears 16-18 

 spicules. The opesium has the form of the zooecium. The ovicell 

 is very small, a little convex, transverse. There are pyriform zooe- 

 ciules between the zooecia; their appearance is sporadic. 



Measurements.— OveBmJ^jP^-^^_^^^'^^^ 



'7^^^^;nJ^2 = 0.60-0.65 mm. 

 ^«^^^^^iz3 = 0.30-0.32 mm. 



Structure. — The interjunctural pores are covered by the ectocyst. 

 Their significance is unknown; they appear to result from an incom- 

 plete calcification. These pores do not furnish a generic character 

 for they are found also in Callopora circumclatJirata Hincks, 1881, in 

 CaulorampTius disjunctus, new species from the Philippines, in HincJc- 

 sina multispinata Canu and Bassler, 1923, and in Mystriopora (?) 

 areolata Canu and Bassler, 1923, both from the California Pleistocene. 

 The zooeciules are always very small and pyriform. Their sporadic 

 arrangement indicates a zoarial function. 



Afinities. — This species differs from HincJcsina multispinata in the 

 much larger micrometric measurements and in the presence of larger 

 and less numerous pores. It differs from Mystriopora (?) areolata in 

 the smaller micrometric measurements. It much resembles Electra 

 di stefanoi Cipolla, 1920, from the Sicilian Pliocene and if the author 

 had figured the ovicell we might have made this identification. 



Biology. — We have observed several cases of total regeneration. 

 The figured ancestrula is surrounded by zooecia closed by a perfo- 

 rated calcareous membrane and with regenerated zooecia. Some of 

 the regenerated zooecia are formed by a zooeciule replacing an ordi- 

 nary zooecium. The larva is very active and afl&xes itself on all 

 marine objects, but principally on the animals with carapace, living 

 or dead. It is thus a parasite of Steganoporella magnilahris. Its 

 large bathymetric extension has no connection with its geographic 

 distribution ; it is probable that it will be found in many other locali- 

 ties. Almost all of our specimens were dead; the only living ones 

 were in reproduction March 15, 1885. 



