156 
BULLETIN' 125, UNITED STATES NATIONAL MUSEUM. 
RHYNCHOZOON CURTUM, new species. 
Plate 4, fig. 14. 
Description. —The zoarium is unilamellar. The zooecia are distinct, separated 
by a deep furrow, elongated, very short, much narrowed behind; the frontal is very 
small, somewhat convex, surrounded with aereolar pores; it bears a small elliptical 
transverse avicularium. The apertura, hidden at the bottom of the peristomie, is 
little visible; it bears a wide rounded rimule. The peristome is salient, wide, formed 
of tuberosities smooth or perforated; it is notched in its proximal part by a triangular 
pseudorimule placed in the median axis of the zooecium. The ovicell is small, short, 
deeply buried, recumbent convex and transverse. 
Affinities —This species differs from Rhynchozoon verruculatum Smitt, 1872, in 
its very short zooecia, in its elliptical and always acuminate avicularium, the length 
of which never surpasses 0.12 mm. In its general aspect the peristome appears to 
occupy half of the zooecium, which thus reduces considerably the length of the frontal 
and which gives such a short appearance. 
Occurrence. —Miocene (Bowden horizon): Sanfo Domingo. 
Holotype. —Cat. No. 68665, U.S.N.M. 
RHYNCHOZOON GRANDICELLA, new species. 
Plate 47, figs. 7, 8. 
Description. —The zoarium incrusts shells. The zooecia are distinct, separated 
by a deep furrow, large , elongated, elliptical. The frontal is a costulated pleurocyst 
surrounded by small areolar pores; it is covered by an avicularian chamber forming a 
truncated tongue above the apertura. The apertura is very oblique, transverse, 
with a wide proximal rimule. The peristomice is very oblique and bears an eccentric 
pseudorimule to the right or left of the avicularian mucro. The ovicell is small, 
globular, opening into the peristomie by a wide orifice. The ancestrular zooecia are 
smaller than the ordinary ones. 
ha =0.15 mm. 
la =0.20 mm. 
Meas urements. —Apertura 
Variations. —The apertura is visible only when the specimen is much inclined. 
The interareolar costules are little salient; on the zoarial margin they are visible only 
under special illumination. 
Affinities. —This species differs from Rhynchozoon longirostris Hincks, 1881, 
also provided with large zooecia, in its dimensions greater than 0.70 mm. and in the 
absence of a frontal avicularium. It differs from Rhynchozoon corrugatum Thornely, 
1905, also deprived of frontal avicularia in its much larger dimensions, in its inter- 
areolar costules, and in its ovicell wanting the two areas. 
Occurrence. —Pleistocene: Rustic Canyon, Santa Monica, California (rare). 
Cotypes. —Cat. No. 68666, U.S.N.M. 
