576 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Genus PERIGASTRELLA Canu and Bassler, 1917. 



1917. Perigastrella CANU and BASSLER, Synopsis of American Early Tertiary Cheilostorne 

 Bryozoa, Bulletin 96, United States National Museum, p. 68. 



The apertura is semicircular. The band of the operculum is on the border. 

 The frontal is surrounded by one or two rows of small areolae ; it is formed of an 

 olocyst supporting a smooth or finely granular pleurocyst. Spines. 

 Genotype.- Perigastrella (Lepralia) labiata Boeck. 1861. 

 Range. Lutetian Recent. 

 The recent species are: 



Perigastrella (Lepralia) labiata Boeck, 1861. 

 Perigastrella (Lepralia) contracta Waters, 1899. 



The fossil species are : 

 Perigastrella (Mucronella) semi- 

 erecta Koschinsky, 1885. 



Perigastrella (Lepralia) grotriani 

 Stoliczka, 1862. 



PERIGASTRELLA ANSATA, new species. 



Plate 14, figs. 18, 19. 



Description. The zoarium incrusts 

 shells. The zooecia are distinct, short, 

 little elongated; the frontal is con- 

 vex and formed of an olocyst per- 

 forated laterally by widely spaced 

 areolae and surmounted by a finely 

 granular pleurocyst. The apertura 

 is formed of a large ogival anter and 

 of a concave poster; the peristome 

 is little salient, very thin, with an in- 

 ferior lip salient or somewhat de- 

 pressed on the frontal. The ovicell is small, recumbent, little salient and hyper- 

 stomial. On the peristome itself there are sometimes two small, round avicularia. 



FIG. 174. Genus Perigastrella Canu and Bassler, 1917 

 A-E. Perigastrella contracta Waters, 1899. A. Zooe- 

 cia, X 25. B, C. Operculum and apertura, X 85. 

 (A-C after Waters, 1899.) D, E. Zooecia and apertura. 

 (After Norman, 1909.) 



, a 



Measurements. Apertura 



mm. 



=0 J2 _ 0-14 mm . 



. \Lz= 0.40 mm. 

 Zooecia U=0.30-0.34mm. 



The form of the apertura, like the handle of a basket, is rather characteristic. 

 Widely spaced areolae have not been observed in any other species. The olocyst 

 and the detachable pleurocyst are clearly visible on figure 19. 



Occurrence. Claiborniaii (Gosport sand) : One mile southwest of Rockville, 

 Clarke County, Alabama (rare). 



Cotypes. at. No. 63853, U.S.N.M. 



