FOSSIL BRYOZOA FROM THE WEST INDIES. 79 



ACANTHODESIA, new genus. 

 Greek : a.Kav6i68ris = full of bristles. 

 The following is a description of this genus: 



No ovicell. The opesium is garnished laterally by small spinous processes 

 and inferiorly by a serrate denticle. 15 tentacles. 



Genotype. Acanthodesia (Flustra) savartii Savigny-Audouin, 1826. 



Range. Lutetian-Recent. 



Another species of this new genus is Membranipora limosa Waters, 

 1908. Waters classified the genotype hi the same group as Mem- 

 branipora hians Hincks, 1885. This is incorrect, since Flustra savartii 

 is deprived of opesiules and its large retractor muscle of the polypide 

 inserted on the median axis of the zocecium assures the symmetry of 

 the opesium; moreover, there is no ovicell. 



The spinous processes are of the same nature as those of the genera 

 Hemiseptella Levinsen, 1909, and Cupularia Def ranee, 1821, but they 

 are very inconstant; in fact they have not been noted on the recent 

 specimens, nor are they very frequent on the fossils. On the contrary, 

 the serrate denticle is rarely found in the fossil examples. 



Acanthodesia savartii forma monilifera, new form. 

 (Plate 2, Figures 2, 3.) 



The following is a description of this form: 



The zoarium is a tube formed of 8 longitudinal rows of zocecia, incrusting 

 the radicells of algae. The zocecia are distinct, much elongated, adjacent at 

 their mural rims, almost rectangular; the mural rim is round, salient, orna- 

 mented with large, regular beads, arranged like a collar around each zocecium. 

 The opesium is elongate, elliptical or oval, surrounded and crenulated by large 

 tuberosities. There is no cryptocyst developed. 



Measurements. Opesium: Ao = 0.34 mm., Zo = 0.18 mm.; zocecium: 1/2 = 0.48 

 mm., fo=0.28 mm. 



This form differs from typical A canthodesia savartii Savigny-Audouin, 

 1826, which has analogous zocecia, in the presence of granulations on 

 the mural rim. Often a large tubercle is developed in the interzocecial 

 angle. But a single specimen of this superb form has been found. 



Occurrence. Lower Miocene (Bowden horizon), Cercado de Mao, 

 (Bluff 3), Santo Domingo. 



Acanthodesia savartii forma texturata Reuss, 1847. 

 (Plate 5, Figures 1 to 5.) 



Flustrellaria texturata Reuss, Die fossilen Polyparien des Wiener-Tertiarbeckens, Haidinger'a 



naturwissenschaftliche Abhandlungen, II, p. 73, plate ix, fig. 1, 1847. 

 Biflustra savarti Smitt, Floridan Bryozoa, collected by Count L. F. de Pourtales, Part I, 



Kongl. Svenska Vetenskaps-Akademiens Handlingar, X, No. 11, p. 20, plate iv, 



figs. 92 to 95, 1872. 

 Flustrellaria texturata Manzoni, I Briozoi fossili del Miocene d'Austria ed Ungheria, II Parte 



Denkschriften der math, natur. Classe der k. Akademie der Wissenschaften, 



XXXVII, 2 Abtheilung, p. 67, plate 13, fig. 43, 1877. 



