178 BXJLUETIN 125, UNITED STATES NATIOKAL MUSEUM. 



imal border being very concave. There are two oral spines and a small oral very 



inconstant aviculariurn. On the deep zooecia the apertura only is visible. 



. ^ (Aa = 0.15mm. 

 Measurements. — Apertura , _ , „ __ 

 ■^ [la =0.1.3 mm. 



Affinities. — ^This species differs from EohporeUa massalis Ulrich and Bassler, 

 1904, in the absence of areolar pores. In the presence of two oral spines it approaches 

 Holoporella hicornis, but differs from it in its larger micrometric dimensions and 

 in the absence of areolar pores. It is also quite close to Cellepora tuberosa Smitt, 

 1872, in the presence of a small oral aviculariurn and in the nature of the frontal; 

 it differs from it in the presence of two spines and in a very different zoarial form. 



Only the figured specimen has been found. More plentiful material will later 

 on permit a more exact study. ' 



The absence of areolar pores may cause our generic determination to be 

 doubted; but they are easily obliterated on the fossils. 



Occurrence. — Miocene (Yorktown formation) : Yorktown, Virgmia (very rare) . 



Holotype.—C&t. No. 68705, U.S.N.M. 



HOLOPORELLA BICORNIS, new species. 



Plate 32, figs. 1-4. 



Description. — The zoarium is formed of large shapeless masses attached to 



algae. The zooecia are erect, salient, very convex; the frontal is smooth, surrounded 



by some much-scattered areolar pores. The apertura is semilunar with a concave 



proximal border; the peristome is wide and bears two large spines. A small, salient 



aviculariurn terminates the median umbo. The deep zooecia have only their 



apertura visible. The interzooecial avicularia are rare and elliptical. Sometimes 



there is a vibraculum on the zooecia. 



-,- J A i f^ = 0.13 mm. 



Measurements. — Apertura, .,„ ^,_ 



^ [ia =0.12-0.15 mm. 



Affinities. — Above many of the apertures a little pore in the form of a Irniar 

 crescent is visible; it has the aspect of vibraculum; it is placed on the distal zooecium 

 or indeed it is interzooecial. Its function is unknown. 



This species resembles Reptocelleporaria siynilis Tuomey and Holmes, but the 

 figure of these authors indicates a greater number of areolar pores. It differs 

 from Holoporella alhirostris Smitt, 1872, in the presence of two large oral spines and 

 in the massive form of the zoarium. In each zoarium there is always a perforation 

 which is the trace of the alga to which the zoarium was attached. This, moreover, 

 is the most frequent habitat of the Celleporidae. 



Occurrence. — Pliocene (Waccamaw marl) : Waccamaw River, Horry Countv. 

 South Carolina (rare) . 



Coty pes. ^C&i. No. 68706, U.S.N.M. 



HOLOPORELLA UMBONATA, new species. 



Plate 40, figs. 8, 9. 



Description. — The zoarium incrusts shells, bryozoa or algae. The zooecia are 

 oriented, distinct, elongate, separated by a deep furrow; the frontal is convex, 

 smooth, surrounded by pores and areolar costules ; a large umbo termmated by an 



