80 GEOLOGY AND PALEONTOLOGY OF THE WEST INDIES. 



The following is a description of this form: 



The cryptocyst is developed on all the zooecia. No spinous processes. No 

 tubercles. The zoarium is unilamellar and subcylindrical. 



Measurements. — Opesia: ho = 0.S5 mm., Zo=0.20 mm.; zocecia: Lz = 0.50 

 mm., Zz = 0.28 mm. 



Variations. — The zoarium incrusts fine algae at their bifurcation; it 

 is therefore unilamellar and subcylindrical. 



The zocecia are elongated, ogival, distinct; the mural rim is striated, 

 salient only in the distal portion; the cryptocyst is large and concave. 

 The opesium is elliptical, very finely denticulated anteriorly; it often 

 bears thin and short spinous processes. 



Smitt figured the serrate denticle on the recent specimens; it never 

 persists on the fossil examples. On the inner face the zocecia are 

 rectangular. 



Affinities. — The presence of the spinous processes differentiates our 

 specimens from Flustrellaria texturata from the European Tortonian, 

 which, according to the figures, does not bear them. 



Occurrence. — Lower Miocene (Bowden horizon), Bowden, Jamaica; 

 Pleistocene or Recent, Vero, Florida. 



Geologic distribution. — Tortonian of Austria-Hungary (Manzoni); 

 Recent off Florida (Smitt). 



Genus OGIVALINA Canu and Bassler, 191 7. 



Ogivalina mutabilis, new species. 



(Plate 1, Figure 4.) 



The following is a description of this species: 



The zoarium is incrusting. The zocecia are elongated, oval, distinct, 

 separated by a deep furrow; the mural rim is thin, smooth, rounded; there is 

 often a small gymnocyst. The opesium is very large, irregular, more often 

 oval. The ovicell is endozocecial, small, little convex. Sometimes there is a 

 small interzocecial fusiform avicularium (?). 



Measurements. — Opesium: ho = 0.60 to 0.70 mm., Zo = 0.30 to 0.45 mm.; 

 zocecium: Lz= 0.75 to 0.95 mm., lz = 0.50 to 0.70 mm. 



The great irregularity of form and zocecial dimensions of this species 

 justifies its name. There are some variations which recall those of 

 Membranipora irregularis Manzoni, 1875, 1 which possesses a mural 

 rim enlarged at the base and also some large interzocecial avicularia. 



The present species differs from the splendid Ogivalina eximipora 

 (Canu and Bassler, 1917) from the middle Jacksonian in its smaller 

 dimensions, in the absence of cryptocyst, and in the presence of a 

 gymnocyst. The avicularium (?) is identical in form and position. 



Occurrence. — Oligocene (Emperador limestone), old quarry, one-third 

 mile north of west of Empire, Panama Canal Zone, D. F. MacDonald 

 and T. W. Vaughan, collectors, 1914, loc. No. 6016. Oligocene (Anguilla 

 formation), southwest side Crocus Bay Hill, Anguilla, Leeward Islands, 

 T. W. Vaughan, collector, 1914, loc. No. 6893. 



1 Briozoi del pliocene antico di Castrocaro, Bologna, p. 10, plate 1, figs. 5 and 8, 1875. 



