52 BULLETIN 16 5, UNITED STATES NATIONAL MUSEUM 



between the zooecia; their orifice is terminal, elliptical, very small, 



and forms a longitudinal slit narrowed laterally; their gymnocyst 



is always smooth. 



Measurements. — 



„ . (£3 = 0.54 mm. A f^=0.07-0.09 mm. 



Zooecia n Apertura 7 Aa 



\lz = 0.27-0.3 mm. L [Za=0.09mm. 



Structure. — The number of superposed lamellae forming the large 

 tubular colonies varies from 5 to 7 ; they are thin and have no con- 

 nection with one another. Each is formed of an adjacent subcolony 

 arising from a false ancestrula, a small zooecium formed from a 

 zooecium of the inferior lamella and overlapped on the other. This 

 is the almost general rule in all the multilamellar cheilostome 

 Bryozoa. 



The zooecial structure is identical with that of Pliophloea sagena 

 Morton, 1834. The opercular valve is very chitinous and perhaps 

 separable, articulated on the two false cardelles serving as a pivot; 

 it was attached to the external ectocyst covering the zooecium. 



It is difficult to recognize the function of the zooeciules. They are 

 analogous to those that we have studied in Distansescharetfa, but 

 they are very different from the interzooecial kenozooecia in Amphi- 

 olestrum dbortivum (Gabb and Horn, 1862), for their orifice is 

 always terminal and never median. Sporadically, especially in the 

 concave portions of the substratum, they replace the zooecia and 

 form groups. Around the false ancestrula, they are isolated and 

 always primoserial. In the zoarial portions farther away they are 

 more numerous and approach one another close enough to form small 

 chains between the cells. 



The gymnocyst of the cells is not always apparent; it disappears 

 under the ovicells or the zooeciules, or indeed it is much reduced 

 with the greater development of the costulated area. The peristome 

 bears three or four small spines scarcely discernible. 



Occurrence. — Vincentown limesand : Rare at Vincentown, N.J., and 

 Noxontown Millpond, Del. 



Ootypes.— U.S.N.M. No. 73929. 



Genus NANNOPORA Lang, 1916 



NANNOPORA(?) MINIMORA, new species 



Plate 12, Figure 7 



Description. — The zoarium encrusts C oscinopleuro.. The zooecia 

 are distinct, separated by a deep furrow, elongated, elliptical, swollen. 

 The frontal is convex and formed by 14 radiating costules orna- 

 mented with pelmatidia and separated by rows of 3 or 4 vacuoles. 

 The aperture is very small, semielliptical, transverse ; the peristome 



