b 



38 BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 



Genus HINCKSINA Norman, 1903. 



(For description, see Bulletin lOG, U. S. National Museum, p. 111.) 



HINCKSINA QUADRISPINOSA, new species. 



Plate 33, fig. 10. 



Description. — The zoarium incrusts shells. The zooecia are distmct, 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. 



,, . /^ • [?io = 0.50-0.60 mm. „ . (is = 0.64-0.70 mm. 



Measurements. — (Jpesia , __. „ „. Zooecia , _ ._ 



^ [to = 0.24-0.26 mm. [/2 = 0.40 mm. 



Affinities. — ^The total regeneration of the polypide 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'Orbignj-, 1S39, 

 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). 



Holotrjpe. —Cat. No. 68445. U. S. N. M. 



HINCKSINA MULTISPINATA, new species. 



Plate 33, fig. 11. 



Description. — The zoarium mcrusts shells. The zooecia are distinct, separated 



by a deep furrow, elongated, oval or pjrriform, 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. 



,, . r> • f?io = 0.24-0.26 mm. „ . [is = 0.40 mm. 



Measurements. — Opesia , _,. _ .,„ Zooecia , „ ._ .„. 



^ 1(0 = 0.14-0.16 mm. [ fz= 0.28-0.34 mm. 



Affinities. — The four distal spines are sometimes smaller and more crowded; 

 the others are regularly distributed around the opesium. The figured specimen 

 only havmg been found, we have not been able to verify whether the ovicell is reaUy 

 endozooecial; a single zooecium shown m our figm-e appears to have this character. 

 We have observed a case of total regeneration of the polypide. 



This species differs from Membranipora variegata Hincks, 1881, in having more 

 than thirteen spines. It differs from Membranipora echinus Huicks, 1884, in the 

 possession of more than two spines in the distal third of the zooecium. It differs 

 from Membranipora echinata D'Orbigny, 1839, m havmg 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. 



