EARLY T1^,P>TIAITY CHEILOSTOME ERYOZOA. 53 



CYSTISELLA, new genus. 



{Cystis, bladder, pouch.) 



The frontal is an olocyst. It bears a very wide avicularian cham- 

 ber in Avhich there is a pair of large glands. The mandibles have 

 a liicida in the middle. (Waters). 



Genotyi>e. — Cystlsella {Por^ella) saccata P)iisk, 1856. 



Range. — Midwayan-Recent. 



" In Porella saccata it [the ovicell] is many-layered, as thin cal- 

 careous layers, presumably gymnocyst [our olocyst] layers, con- 

 tinually grovv^ over the 0(£cium, not only from the distal zooecium 

 but also from the two neighboring zocecia, and w^e can see, as a rule, 

 three, distinctly separated, thin covering plates on their surface." ^ 



CYSTISELLA MIDWAYANICA. new species. 



Plate 5, fig. G. 



Description. — The zoarium incrusts shells. The zooecia are dis- 

 tinct, somewhat elongated, hexagonal, separated by a furrow or a 

 thin salient thread ; the frontal is very convex and very finely granu- 

 lated. The peristome is thin, little salient in its distal part ; it bears 

 some spines; the peristomice is elliptical and deformed inferiorly by 

 the avicularium. The aviculariam forms a long chamber, median 

 and conical; its orifice is little circular and turned toward the 

 apertura. 



MeasureTThents. — Peristomice / a\ i * 



l/pe=0.14mm. 



rj • fZs=0.40 mm. 

 Zooecia , ^ ^^ 



1 fe=0.30mm. 



Occurance.—Midyvaynn (Clayton limestone) : Luverne, Crenshaw 



County, Alabama (very rare). 



One mile west of Fort Gaines, Georgia (rare). 



Type.— Cat. No. G2902, U.S.N.M. 



Genus PORELLA Gray, 1848. 



1848. Porella Gray, List of British Animals in collection British Museum. 

 Centrouiae, pp. 127, 148. 



The ovicell opens into the peristomie; it is porous, imbedded in 

 the distal zocecium. The apertura is semilunar. Neither lyrule nor 

 cardelles. The operculum is almost straight in its proximal part, 

 with rounded corners; there is a muscular prominence a little dis- 

 tance from the edge. In front of the apertura there is an avicu- 

 larium ; the mandible is semicircular and has well-marked thickenings 



1 Leviasen, JHorp'aological and Systematic Studies on the Cheilostomatous Bryozoa, p. 



336. 



