NORTH AMERICAN EARLY TERTIARY BRYOZOA. 609 



HOLOPORELLA DAM1CORNIS. new species. 



Plate 77, figs. 1-7. 



/description. The zoarium incrusts, first, the radicels of an alga to form an 

 attachment for suspension; it then develops freely into a small irregular mass 

 ornamented with horns of greater or less length. The superficial zooecia are little 

 erect, simply oblique; the frontal is smooth and quite convex; it is terminated by 

 an aviculiferous umbo more or less developed ; the avicularium is open under the 

 umbo toward the apertura. The apertura is semilunar, very finely crenulated ; the 

 anter is separated from the poster, which is smaller and concave, by two minute 

 cardelles. The ovicell is hyperstomial, very salient, globular, smooth, provided 

 with a large opening. The deep zooecia are rare; they have no frontal: their umbo 

 forms an interzooecial prominence. The interzooecial avicularia are large, ellip- 

 tical, with pivot. The incomplete zooecia are suborbicular and not rare 



iha 0.15 mm. 

 Measurements. Apertura L ., 



{?a=0.13mm. 



Variations. The zoarium with its eccentric shape is very curious; no one 

 specimen resembles another and yet all have a general indefinable facies which 

 permits their immediate determination. Evidently this is not altogether a phenome- 

 non of symbiosis in its entirety, but it is very close to it. It is even probable that 

 the alga chosen by the larva was always the same and that its disappearance has 

 caused at the same time the death of the Cellepore. 



The umbo is rather fragile and is easily broken (fig. 6) ; often it is even not 

 developed at all (fig. 5). 



Figure 7 shows the ordinary cumulation of the zooecia. Such sections indicate 

 the complicated structure of the zooecial walls, which sometimes appear to con- 

 tain dietellae. The interpretation of the sections of the Cellepores are really 

 problems of descriptive geometry. 



Affinities. In its zooecia this species somewhat resembles Holoporetta albi- 

 rostris Smitt, 1872, which still lives in the Floridan waters. It differs from it 

 however in its symmetrical umbo and the absence of areolae. 



Occurrence. Jacksonian (Zeuglodon zone) : Suck Creek, Clarke County, Mis- 

 sissippi (rare) ; Cocoa post office, Choctaw County, Alabama (common) ; Jack- 

 son, Mississippi (very rare). 



Cotypes.Ca.t. No. 64222, U.S.N.M. 



HOLOPORELLA SEPARATA, new species. 



Plate 76, figs. 13-19. 



Description. The zoarium is massive and is formed of small irregular masses 

 fixed to bryozoa, to the convexity of shells, or to the radicells of algae. The super- 

 ficial zooecia are erect, suborbicular, separated one from the other; the frontal is 

 smooth. The apertura is orbicular and formed of a large, semilunar anter sepa- 



.ws'.i:i ID Bull. 10(3 3!) 



