198 BXJLLETIN 125, UNITED STATES NATIONAL, MUSEUM. 



TUBULIPORA TUBA Gabb and Horn, 1862. 



Plate 42, figs. 18-23. 



1862. Semiluhigera tuhaGKBB and Horn, Monograph Polyzoa of the Secondary and Tertiary forma- 

 tions of North America, Journal Academy Natural Sciences Philadelphia, ser. 2, vol. 5, 

 p. 169, pi. 21, fig. 57. 



1910. TubuUpora occidentalii Robertson, Cyclostomatous Bryozoa of the west coast of North Amer- 

 ica, University of California Publications, Zoology, vol. 6, p. 249, pi. 22, figs. 29-31. 



Measurements. ^Dinmeter of the peristome, 0.12 mm. 



Variations. — -The zoarium creeps on algae, with generally flabelliform fronds: it 

 sometimes entirely sun'ounds the delicate radicells and thus becomes tubular. We 

 have observed some specimens on otlier bryozoa. 



The fascicles are monoserial or biserial; they have a large number of tubes, 

 from 6 to 20; they are often arranged on each side of the zoarial axis in rather 

 irregular order. 



The ovicell is large and is inserted between six or eight fascicles. The oecios- 

 tome is a very small tube, quite salient, adjacent to the first tube of a fascicle. 



Affinities. — This species differs from Tuhulipora fascicuUfera Hincks, 1884, in 

 its long fascicles composed of more than six tubes and in its long capillary oecios- 

 tome. 



Occurrence. — Pleistocene: Santa Monica (Rustic Canyon), (rare), Dead Mans' 

 Island, off San Pedro (rare), and Santa Barbara (rare), California. 



Haiitat. — Pacific: Off California, and the Queen Cliarlotte Islands. 



Plesiotype.—CsLi. Nos. 68738, 68739, U.S.N.M. 



Genus IDMONEA Lamouroux, 1821. 



(For description, see Bulletin 106, U. S. National Museum, p. 770.) 



IDMONEA DISPAR, new species. 



Plate 41, figs. 6-10. 



Description. — The zoarium is free, bifurcated, with subcylindrical section; the 

 branches are undulated and at a bifurcation; they are not equal. The fascicles 

 are alternate or almost opposite and diverge from eacli side of the median crest. 

 The tubes are visible, convex, and three or four in number to a fascicle; the 

 peristome is thin and orbicular. 



Measurements. — Width of salient fascicles 0.14 mm. 



Width of little salient fascicles 0.20 mm. 



Diameter of first zooecium (on the zoarium) 0.18 mm. 



Distance between the fascicles 0.40-0.60 mm. 



Zoarial diameter. 0.80 mm. 



Affinities. — This species is quite well characterized by the inequality of the 

 branches at the bifurcations; there is always one a little smaller than the other. 



Occurrence. — Pleistocene: Santa Monica (Tremochal Canyon) ,California (com- 

 mon). 



Coty pes. —C&t. No. 68740, U.S.N.M. 



