NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
21 
tudinal rows in 3 mm. Opesium elongate oval, generally about twice as long as wide. Walls nearly 
always a little less than half the width of’the opesium, with a median channel, the ring-like elevation 
enclosing the opesium uniformly elevated except across the anterior end where it is higher and obliquely 
arched and elevated beneath, probably to form a cover for an ooecium, and is usually surmounted by 
a transverse rib terminating at each end in a small rounded prominence. Rarely the space of an ordinary 
zooecium is taken up by a cell having a thicker wall and a smaller aperture varying from elongate to 
nearly circular, while in one instance, a small cell with an oblique opening, narrowed distally, is 
wedged in between three zooecia. 
Measurements. —Opesia 
ho = 0.36 mm. 
lo = 0.20 mm. 
Zooecia' 
Lz = 0.50 mm. 
. lz = 0.32 mm. 
Variations. —Our micrometric measurements represent the average; in reality 
as in all the Membranipores the variations are considerable. The mural rim is 
always somewhat wider in the proximal portion; the separating furrow is deep; 
the opesium is finely crenulated. The two distal tubercles are placed generally 
on the termen of the mural rim, but frequently they are attached to the exterior 
slope and appear there as inserted in the interzooecial angles. We have not yet 
discovered regenerated zooecia. 
We present a new photograph of the type of this species winch brings out the 
surface ornament and especially the tubercles more clearly. The species has 
resemblance to both Conopeum and Membranipora, but the apparent absence of 
the two impressions on the dorsal wall of the zooecium, characteristic of Conopeum, 
and the presence of the spines of Membranipora cause us to refer the species to 
Membranipora in its restricted sense. 
Occurrence. —Miocene (Calvert formation): Reed’s, Maryland (very rare). 
Miocene: Kuhns, Carteret County, North Carolina (rare). 
Plesiotype. —Cat. No. 68403, U.S.N.M. 
MEMBRANIPORA SPICULATA, new species. 
Plate 9, fig. 1. 
Description. —The zoarium encrusts species of Cellepora. The zooecia are 
distinct, separated by a deep furrow, elliptical, elongated; the mural rim is thin, 
salient, flat, bearing two distal tuberosities and two pairs of lateral spicules which 
are conical and very salient. The opesium is of the same form as the zooecium. 
Measurements. —Opesiaj 
ho = 0.32 mm. 
Zo = 0.18 mm. 
Zooecia* 
\Lz = 0A0 mm. 
[ lz = 0.?>0 mm. 
Affinities. —In its lateral spicules this species has much resemblance to Spiralaria 
denticulata Busk, 1852, but it differs from it in the absence of an endozooecial ovicell 
and in the presence of two lateral pairs of spicules. Hincksina serrata MacGillivray, 
1881, also has a similar aspect, but in the present species we have not observed 
either the ovicell or interzooecial avicularia. The spicules are rarely erect; they 
are more or less curved in the form of a claw. The distal tuberosities are often 
transformed into spicules. It is therefore rather probable that this species bears 
an ovicell. But a single specimen has been found. 
Occurrence. —-Miocene: Kuhns, Carteret County, North Carolina (rare). 
Holotype. —Cat. No. 68404, U.S.N.M. 
