124 BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 



Occurrence. — Pleistocene: Santa Monica (Long Wharf Canyon) (rare), Santa 

 Barbara (common), and .San Pedro (rare), California. 



Ilabitat. — Queen Charlotte Islands and coast of California. 

 Plesiotypes. —C&t. Nos. 68597, 68598, U.S.N.M. 



MICROPORELLA VIBRACULIFERA Hincks, 1883. 



Plate 36, figs. 11, 12. 



1883. Microporella ciliata forma vibraculifera Hincks, Report on the Polyzoa of the Queen Charlotte 

 Islands, Anuals 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 fur 

 Naturgeschichte, vol. 50, pt. 1, p. 38, pi. 3, fig. 5. 



-,, . . ^ fi^a=O.OGmm. „ . fLs =0.50-0.60 mm. 



Measurements. — Apertura , „,^ /ooecia , „„. ^ ,„ 



^ [(a =0.12 mm. [ (2=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. 



Ilabitat. — 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. Reploporina 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. 



ij- , A i. [Aa =0.06 mm. „ . fLs =0.60-0.80 mm. 



Measurements. — Apertura , ^ , ^ Zooecia , „ „ 



^ [to =0.12 mm. lZ2=0.50mm. 



Affinities. — Gabb and Horn's figure is very characteristic; the mandible of the 

 avicularium is obhque in relation to the zooecial median a.xis so that the whole 

 avicularium convexity appears bent toward this same axis. Tliis is the exact case 

 in our specimens. However, they bear only six large hollow spines instead of eight 

 shown on the figm-es 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. 



Occ«7Tence.— Pleistocene : Santa Monica (Rustic Canyon) (rare) and Santa 

 Barbara, California (Gabb and Horn). 



Plesiotype.—C&t. No. 68601, U.S.N.M. 



