520 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Genotype. Gigantopora lyncoides Ridley, 1881. 

 Range. Jacksonian Recent. 



GIGANTOPORA FILIFORMIS, new species. 

 Plate 66, figs. 30-35. 



Description. The zoarium is free, filiform, somewhat compressed, bifurcated, 

 with two rows of alternate zooecia on the anterior face; the dorsal is smooth and 

 convex. The zooecia are indistinct; the frontal is smooth and little convex. The 

 apertura is formed of a semilunar anter and of a straight proximal border notched 

 by a small linear rimule; the peristomie is formed by two large lateral peristomial 

 avicularia, which can be transformed into bifurcated spines. An arch which unites 



FIG. 153. Genus Gcphyrophora Busk, 1SS4. 



A-G. Gcplii/rophora poli/morpha Busk, 1SS4. A. Zooecia, X 25. (After Busk, 1SS4.) 

 B. Zooecia, X 25. O, D. Longitudinal section, X 4 arid X 25, showing the ovicell (ov) opening 

 in the peristomie above the operculum (op). E. Operculum, X 85. (B-E after Waters, 1889.) 

 F, G. Operculum and avicularian mandible, X 85. (After Waters, 1887.) 



these two avicularia separates the peristomice from the spiramen. The hyper- 

 stomial ovicell is small, globular, smooth. 



\ha=OMmm. . fl2= 0.40-0.45 mm. 



Measurements. Apertura J, ... Zooecia, 



|i(7=0.04 mm. (/s=(j.6vmm. 



Variations. -The spiramen is rare on our specimens; some zooecia only are 

 furnished with it (fig. 35). The dorsal (fig. 34) is smooth; nevertheless it is 

 porous on one of our specimens. The avicularia have no pivot, but they have two 

 lateral denticles; they are quite salient. 



Affinities. The mode of formation of the spiramen is identical with that of 

 Gigantopora lyncoides Ridley, 1881. It differs from it in its peristomial avicu- 

 laria, which are not vibraculoid and which are much larger, and in its spiramen, 

 which is not much larger than the apertura. 



