NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 31 



ACANTHODESU SAVARTI Savigny-Audoain, 1826. 



1812. Flustra savarti Saviony, Description de I'Egypte, Polj^ses, pi. 10, fig. 10. 

 1826. Flustra savarti Audouin, Explication sommaire des planches de Polypes de I'Egypte et de 

 la Syrie, p. 240. 



The variations in form and size of this species are extraordinary. We group 

 them around some principal forms, but it is evident that the same zoarium may 

 exhibit all of them. These forms are as follows : 



1. Forma typica. The opesium is crenulated and elongated; the large zooecia 

 have a cryptocyst. The zoarium is incrusting, unilamellar or bilamellar. 



2. Forma texturata. The cryptocyst is developed on all the zooecia. No 

 areal spines. No tubercles. The zoarium is unilamellar and subcylindrical. 



3. Forma reyti. The zooecia are irregular. There are areal spines. No 

 cryptoc3^st. No tubercles. The opesium is denticulated and not crenulated. The 

 zoarium is unilamellar and subcylindrical. 



4. Forma monilifera. Like typica, but the mural rim is beaded. The zoarium 

 is unilamellar and subcylindrical. 



5. Forma delicatula. The cryptocyst is short. There are areal spines. The 

 zoarium is bilamellar. 



6. Forma bifoliata. There are areal spines. The opesium is surrounded by 

 a sort of sahent collar. The zoarium is bilamellar. Tubercles at the angles. 



These various forms and occurrences are noted under the following headings : 



ACANTHODESIA SAVARTI forma TYPICA. 



Plate 11, figs. 1-3. 



The opesium is crenulated and elongated ; the large zooecia have a cryptocyst. 

 The zoarium is encrusting, unilamellar or bilamellar. 



Our few American specimens are encrusting. The zooecia are less elongated 

 than in the forma monilifera and less spinous than the forma reyti. The micro- 

 metric variations are very great. The granulations are as beautiful as in the other 

 two forms. 



Occurrence. — Miocene (St. Mary's formation) : Bowler's wharf, Kappahannock 

 River, 18 miles above Urbana, Middlesex County, Virginia (rare). Miocene (York- 

 town formation): Near Suffolk Virginia (rare). Pleistocene: Vero, Florida 

 (common) . 



Plesiotypes.— Cat. No. 68426, U.S.N.M. 



ACANTHODESIA SAVARTI forma REYTI Canu. 1909. 



1909. Membranipora reyti Canu, Lea Bryozoaires fossiles des Terraines du Sud-Ouest de la France; 

 III Burdigalien, Bulletin de la Soci6t6 G^ologique de France, ser. 4, vol. 9, p. 443, pi. 15, 

 fig- 2. 

 1909. Membranipora savarti C.\NU, Les Bryozoaires fossiles des Terraines du Sud-Ouest de la France; 

 III Burdigalien, Bulletin de la Soci6t6 GiSologique de France, ser. 4, vol. 9, p. 444, pi. 15, 

 fig. 3. 



, ^. . fi^o = 0.34-0.50 mm. ^ . [Z3 = 0.50mm. 

 Measurements.-Opesial ^ ^ o_20-0.30 mm. ^''"^"^ Iz = 0.40 mm. 



