NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 175 



quite variable; it presents very frequently an excentric pseudosinus, as in the 

 specimens dredged by the Challenger at Heard Island. This is occasioned by the 

 very irregular development of a spiniform mucro. The latter is very fragile and 

 never exists on our fossils; it is scarcely visible, and then only on the deep zooecia. 

 The frontal is smooth and garnished laterally with very small areolar pores (pi. 32, 

 fig. 8) which are rather easily obliterated (pi. 32, fig. 7). The interzooecial avicu- 

 larium is spatulate ; its distribution on the zoarium is very inconsistent. 



The zoarium is always attached to algae; it creeps above or indeed completely 

 around them to form masses of 3 centimeters in diameter. The depth at which 

 it is dredged therefore gives no indication of its hydrostatic capacities if it is not 

 living; the disappearance of the algae buries the zoarium in the depths where 

 it did not live. The ancestrular zooecia are oriented (pi. 32, fig. 10) and the ances- 

 trula emits five buds. The tuberosities observed on certain zoaria come from the 

 greater development of certain zooecial groups. 



Occurrence. — Oligocene (Emperador limestone) : One-third mile north of Em- 

 pire, Panama Canal Zone (rare). Oligocene (Anguilla formation): Southwest side 

 of Crocus Bay, x\jiguilla, Leeward Islands (rare) . Lower Miocene (Bowden marl) : 

 Bowden, Jamaica (very common). Pliocene (Calooshatchee marl): Shell Creek, 

 De Soto County, and Monroe County, Florida (very common). 



Geological distribution. — Miocene of Australia; Pliocene of New Zealand. 



Hahitat. — Atlantic: Off Florida (24-56 meters). Indian Ocean: Heard Island 

 (121 meters). Pacific: Off Australia (to 13 meters). 



Plesiotypes.~Ca,t. Nos. 68695-68697, U.S.N.M. 



HOLOPORELLA PARVULA, new species. 



Plate 24, figs. 10-13. 



Description. — The zoarium is free, subcylindrical, irregularly branched. The 



zooecia are very small, heaped upon each other, irregular, provided with a small 



umbo before the apertura and surrounded by some areolar pores. The apertura is 



very small, semielliptical, transverse, surrounded by one to four small orbicular 



avicularia. 



,, , . , \ha = 0. 08 mm. 



Measurements. — ^Apertura, __ . 



Affinities.— In its general aspect this species may easily be confounded with 

 Holoporella maculata Ulrich and Bassler, 1904, and with Holoporella minuta, new 

 species. It dift'ers from both of these in its free and cylindrical zoaria (and not 

 attached to sliells), and in the presence of the small avicularia which surround the 

 apertura. 



Occurrence. — ^Miocene (Duplin marl) : Cape Fear River, 28 miles northwest of 

 Wilmington. North Carolina (rare). 



Holoiype.— Cat. No. 68698, U.S.N.M. 



HOLOPORELLA ROSTRIFERA, new species. 



Plate 24, fig. 14. 

 Description. — The zoarium incrusts shells and forms small spiny masses. The 

 zooecia are indistinct, erect; the frontal is convex, small, surrounded by a double 

 row of areolar pores and often with costules directed toward the frontal rostrum 



