162 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
type on account of the transformation of the opesium into an aperture and of the 
opercular valve into a true operculum. 
Within the broken ovicells there are spines. This is an absolute impossibility. 
One must therefore suppose that the spines are reformed after the destruction of 
the ovicell. This destruction is frequent everywhere in the bryozoa after the 
expulsion of the larvae ; the animal economizes its carapace in this way. 
Occurrence. — Upper Jacksonian (Ocala limestone) : Old factory, l-i miles 
above Bainbridge, Georgia ( very rare). 
Holotype.— Cat. No. 63932, U.S.N.M. 
AMPHIBLESTRUM CURVATUM, new species. 
Plate 81, fig. 4. 
The zoarium incrusts other bryozoa. The zooecia are distinct, wide, pyriform ; 
the cryptocyst is concave, finely granular, shorter than the opesium. The opesium is 
anterior, pyriform. The ovicell is globular, salient, hyperstomial, never closed by 
the operculum, ornamented with a large frontal, granular callosity. The avicu- 
larimn is interzooecial and curved; the pivot is formed by two small lateral 
denticles. 
Measurements. — Opesiai^ 0 mm ' 
? 0 =O .12 mm. 
Zooecia 
Lz— 0.30-0.35 mm. 
fe=0.25 mm. 
Affinities. — -The avicularium is analogous to that in the recent (J allop or a cur- 
virostris Hincks, 1861. (See fig. 37.) We have copied figures after Waters to show 
the reader how this sort of avicularium must be restored. It must not be con- 
founded with the onychocellarium having a membranous expansion. The paleon- 
tologist is always obliged to compare the fossil vestiges with similar organs of the 
recent species. 
This species differs from Callopora curvirostris Hincks, 1881, in which the 
mural rim is very thin, by the presence of its large cryptocyst. 
It differs from Amphiblestrum flammcum in its smaller dimensions and its 
curved avicularia. 
Occurrence. — Vicksburgian (“Chimney rock” of Marianna limestone) : One 
mile north of Monroeville, Alabama (rare). 
Holotype. — Cat. No. 64235, U.S.N.M. 
KEY TO SPECIES OF AMPHIBLESTRUM. 
I [Opesium semilunar _ A. orMculatum. 
[Opesium oval or elliptical 2 
,, [Avicularia curved : A. curvatum. 
[Avicularia straight 3 
g [Two pores at the base of the zooecium A. Mporos-um. 
| No pores at the base of the zooecium 4 
4 [Zooecia small elongated (Ls— 0.35 mm.) small avicularia A. productum. 
[Zooecia large and wide (L?=0.4(M).60 mm.) large avicularia 5 
g [Mural rim complete, long, distal canal on the avicularium A. flammeum. 
[Mural rim incomplete, very short, distal canal on the avicularia A. patens. 
