38 
BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 
Genus HINCKSINA Norman, 1903. 
(For description, see Bulletin 106, U. S. National Museum, p. 111.) 
HINCKSINA QUADRISPINOSA, new species. 
Plate 33, fig. 10. 
Description. —The zoarium incrusts shells. The zooecia are distinct, separated 
by a very deep furrow, large, elongated, elliptical; the mural rim is convex, thin, 
granulated, ornamented with four distal, hollow spines. The opesium has the same 
form as the zooecium. The ovicell is endozooecial, very small, scarcely salient. 
Affinities. —The total regeneration of the polvpide is frequent and manifests 
itself, as is customary by a double mural rim. This species differs from Membren- 
doecium grande in the presence of four distal spines. It differs from Membranipora 
echinata D’Orbigny, 1839, in the presence of four (and not six) distal spines and in 
a much smaller ovicell. It differs from Membranipora irregularis D’Orbigny, 1839, 
of which it has the zooecial form, in its endozooecial and very small ovicell. Our 
specimen which showed the ovicell was not in a condition to be photographed. 
Occurrence. —Pleistocene: Santa Monica (Rustic Canyon), California (rare). 
Holotype. —Cat. No. 68445. U. S. N. M. 
HINCKSINA MULTISPINATA, new species. 
Plate 33, fig. 11. 
Description. —The zoarium incrusts shells. The zooecia are distinct, separated 
by a deep furrow, elongated, oval or pyriform, provided with a small convex and 
smooth gymnocyst; the mural rim is thick, round, salient and bears 16 to 18 large, 
hollow spines; the opesium is anterior, oval, entire. 
Affinities. —The four distal spines are sometimes smaller and more crowded; 
the others are regularly distributed around the opesium. The figured specimen 
only having been found, we have not been able to verify whether the ovicell is really 
endozooecial; a single zooecium shown in our figure appears to have this character. 
We have observed a case of total regeneration of the polypide. 
This species differs from Membranipora variegata Hincks, 1881, hi having more 
than thirteen spines. It differs from Membranipora echinus Hincks, 1884, in the 
possession of more than two spines in the distal third of the zooecium. It differs 
from Membranipora echinata D’Orbigny, 1839, in having more than six spines. 
It differs from Membranipora pyrula Hincks, 1881, in its smaller dimensions and in 
the presence of a greater number of spines. 
Occurrence. —Pleistocene: Santa Barbara, California (very rare). 
Holotype.—' Cat. No. 68446, U.S.N.M. 
