124 
BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 
Occurrence. —Pleistocene: Santa Monica (Long Wharf Canyon) (rare), Santa 
Barbara (common), and San Pedro (rare), California. 
Habitat. —Queen Charlotte Islands and coast of California. 
Plesiotypes. —Cat. Nos. 68597, 68598, U.S.N.M. 
„ , . , [ha =0.06 mm. 
Measurements. —Apertura' ^ 
MICKOPORELLA VIBRACULIFERA Hincks, 1883. 
Plate 36, figs. 11, 12. 
1883. Microporella ciliata forma vibraculifera Hincks, Report on the Polyzoa of the Queen Charlotte 
Islands, Annals and Magazine of Natural History, ser. 5, vol. 11, p. 15, pi. 17, fig. 2. 
1890. Microporella ciliata, var. vibraculifera Ortmann, Die japanische Bryozoen-Fauna, Archiv fiir 
Naturgeschichte, vol. 50, pt. 1, p. 38, pi. 3, fig. 5. 
r, . \Lz =0.50-0.60 mm. 
ZOOGClft] ti o < A 
mm. I Iz =0.34-0.40 mm. 
Variations. —There are six large hollow spines. The ovicell and the frontal 
bear large tremopores. The avicularium is large, salient, tuberous, placed laterally 
and lower than the ascopore; the mandible is placed transversally. The ovicell is 
costulate. The organ originally called vibraculum by Hincks is in reality an 
avicularium with very long and setiform mandible. There is often a pivot. 
Affinities. —This species differs from Microporella ciliata Linnaeus, 1759, in the 
presence of six large hollow spines and in larger micrometric measurements. It 
differs from Microporella fallax Canu, 1904, in its larger avicularium placed very 
near the ascopore. It differs from Microporella eustomata Gabb and Horn, 1862, 
in its transverse avicularium. 
Occurrence. —Pleistocene: Santa Monica (Rustic Canyon) (rare), Dead Mans 
Island off San Pedro (rare), and Santa Barbara (very rare), California. 
Habitat. —Queen Charlotte Islands and Japan (113-405 meters). 
Plesiotypes. —Cat. Nos. 68599,68600, U.S.N.M. 
MICROPORELLA EUSTOMATA Gabb and Horn, 1862. 
Plate 36, fig. 13. 
1862. Reptoporina eustomata Gabb and Horn, Monograph of the fossil Polyzoa of the Secondary 
and Tertiary formations of North America, Journal Academy of Natural Sciences of Phila¬ 
delphia, ser. 2, vol. 5, p. 144, pi. 20, fig. 26. 
Measurements. —Apertura- 
ha =0.06 mm. 
la =0.12 mm. 
Zooecia 
Lz =0.60-0.80 mm. 
Iz =0.50 mm. 
Affinities. —Gabb and Horn’s figure is very characteristic; the mandible of the 
avicularium is oblique in relation to the zooecial median axis so that the whole 
avicularium convexity appears bent toward this same axis. This is the exact case 
in our specimens. However, they bear only six large hollow spines instead of eight 
shown on the figures of the American authors. The frontal and the ovicell are 
garnished with large tremopores. The ovicell is preceded by a sort of tubular 
turret, at the base of which is buried the operculum. The avicularium is curved 
and always has a pivot. 
This species differs from Microporella vibraculifera Hincks, 1883, in its oblique 
and nontransverse avicularium. It differs from all the other species of Microporella 
in its large avicularium. 
Occurrence. —Pleistocene: Santa Monica (Rustic Canyon) (rare) and Santa 
Barbara, California (Gabb and Horn). 
Plesiotype. —Cat. No. 68601, U.S.N.M. 
