520 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Genotype. — Gigantopora lyncoides Riclley, 1831. 
Range. — J acksonian — Recent. 
GIGANTOPORA FILIFORMIS, new species. 
Plate 66, figs. 30-35. 
Description. — The zoarium is free, -filiform , somewhat compressed, bifurcated, 
with two rows of alternate zooeeia on the anterior face; the dorsal is smooth and 
convex. The zooeeia 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 Gephyrophora Busk, 1SS4. 
A-G. Gephyrophora polymorpha Busk, 1S84. A. Zooeeia, X 25. (After Busk, 1884.1 
B. Zooeeia, X 25. 0, D. Longitudinal section, X 4 and 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. 
Measurements. — -Apertura 
Zw=0.04mm. 
A7=0.04 mm. 
„ . \Lz= 0.40-0.45 mm. 
Zooeeia , A OA 
fe=0.30mm, 
Variations. — The spiramen is rare on our specimens; some zooeeia 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. 
