l(i 2 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, H miles 

 above Bainbridge, Georgia (very rare). 



fJolotype.Cat. No. 63932, U.S.X.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- 

 larium is interzooecial and curved; the pivot is formed by two small lateral 

 denticles. 



. , ^0=0.12-0. lo mm. r , 

 MeasuTi ///< ..s. Opesia , Zooecia 



'Z0=0.12 mm. 



Zs= 0.30-0.3o mm. 

 7s=0.25 mm. 



Affinities. The avicularium is analogous to that in the recent CaMopora cur- 

 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 Mariauna lime-rone): One 

 mile north of Monroeville, Alabama (rare). 



Holotype.Cnt. Xo. 64235, U.S.N.M. 



KEY TO SPECIES fir AMrHIKLESTHUM. 



I [Opesium seniilnn:ir_. A, I'l 



< ipesiuru oval or elliptic-ill-- 2 



., fAvicularia curved I. m 



I Avicularia straight - ." 



., [Two pores at the base of the zooeeiuni-- 1. iii/niroxiini. 



| No pores at the base of the zooecium --4 



[Zooeeia small elongated (L~ o.'.-\r, mm. I small iivic-iil:iri:i__ I. i>rrnliirtiim. 



[Zooecia large and wide (1/^=0.40-0.60 mm. i large avicularia_. 



_ [Mural rim complete, long, distal canal on the ;mcularimn__ . .1. fld 



plural rini iiic'iunplctc. very short, disial i-Miial nil the avicularia__ I. i>nt< H*. 



