182 BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 



Genus CELLEPORA Linnaeus, 1767. 



We retain the ancient name Cellepora for those species, which at present can not 

 be placed more definitely. 



CELLEPORA MINUTA, new species. 



Plate 25, figs. 10-13. 



Description. — The zoarium incrusts in thick masses gastropod moUusks; it 

 sometimes emits irregular and ramified branches. The zooecia are small, little 

 distinct, poorly oriented, little erect; the frontal is little convex, more or less large, 

 surrounded by a line of small areolar pores separated by short costules and formed 

 of a pleurocyst detachable from the subjacent olocyst. The apertura is small, sub- 

 orbicular; two small cardelles, almost median, separate the anter from the somewhat 

 smaller poster. The incomplete zooecia are rare. A very salient small avicularium 

 is between the apertures. 



is = 0.35 mm. 



Measurements. — Apertura 



ha = 0.08 mm. ,, 



7 r, /^-, Ziooecia 



Za = 0.07 mm. 



Iz = 0.30 mm. 



Affinities. — The phenomenon of symbiosis is characteristic of this species. It 

 apparently can live only on a gastropod; we have not a single specimen fixed on 

 any other substratum. The zoarium envelopes the mollusk and ends by killing it; 

 it is rather regular and frequently presents tuberosities formed of raised zooecia. 

 We always have trouble in understanding the selective faculty of the larvae; the 

 latter can not really choose their substratum of fixation; is it therefore a biochemical 

 reaction which permits them to subsist only on the shells of gastropods? 



This species is quite close to Cellepora maculata Ulrich and Bassler, 1904, in its 

 zoarium which affects the same phenomenon of symbiosis, in its small dimensions 

 and the absence of deep zooecia. Confusion of the two is very easy, but the present 

 species differs in the almost general presence of a single row of areolar pores and 

 especially in the very constant occurrence of small interzooecial avicularia, which 

 are tubular and very salient. 



A sort of umbo, more or less salient, sometimes partiall}- covers the poster. 

 When we know the ovicell it will perhaps be necessary to place this species in a new 

 genus. 



Occurrence. — ^Miocene (Duplin marl): Wilmington, North Carolina (rare). 

 Pliocene (Waccamaw marl) : Waccamaw River, Horry County, South Carolina 

 (rare) . 



Coty pes. ~Cs.i. No. 68715, U.S.N.M. 



CELLEPORA MACULATA Ulrich and Bassler, 1904. 



Plate 25, figs. 14-20. 



1904. Lepralia maculata Ulrich and Bassler, Bryozoa Miocene, Maryland Geological Sur\ev, p. 

 423, pi. 114, figs, 8, 9; pi. 118, fig. 7. 



Ulrich and Bassler's original description follows. 



Zoarium beginning as a thin shoot on shells of small gastropoda to which other layers are added until 

 masses as much as 2 inches in diameter result. Surface of masses generally exhibiting more or less dis- 

 tinct, usually elevated, clusters of zooecia slightly larger than those occupying the intermediate spaces. 

 Zooecia convex, subovate, not sharply separated nor exliibiting any obvious plan of arrangement; when 

 in rows a'DOUt six occur in 2.0 mm. Orifice not terminal but situated in the anterior half, rounded and 



