FOSSIL BRYOZOA FROM THE WEST INDIES. 87 



Genotype. — Corynostylus labiatus, new species. Lower Miocene. 



This genus has no recent equivalent; but its structure is easy to 

 interpret. The two condyles serve as a hinge for the strongly chitinized 

 opercular valve. The lower part of the opesium placed below served 

 evidently as passage for the opesiular fibers attached to the ectocyst. 

 The deep cavity of the cryptocyst served as a hydrostatic apparatus 

 for the entrance and exit of the polypide. Like most of the articulated 

 genera, this one probably was fastened on large mobile algae. 



Corynostylus labiatus, new species. 



(Plate 2, Figures 11 to 13.) 



The following is a description of this species: 



The zoarium is articulated and formed of long, regular segments. The 

 segments are compressed, bilamellar, formed of three longitudinal rows of 

 zocecia on each side. The zooecia are elongate, oval, distinct, rounded in 

 front, narrowed behind, and are provided with a convex gymnocyst with 

 large pores; the mural rim is thick, regular, granular. The opesium is elongate, 

 oval, provided with a proximal, salient lip placed between two rounded 

 opesiular indentations. The two condyles are quite salient. The cryptocyst 

 is deep and smooth. 



Measurements. — Opesium: ho=0.12 nun., Zo=0.10 mm.; zocecium: Lz=0.50 

 mm., lz=0.2Q to 0.28 mm. 



Affinities. — The first zocecium of each segment is radicular; it gives 

 rise to 3 polypidian zooecia. 



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

 (Bluff 3), Santo Domingo. 



Corynostylus ellipticus, new species. 

 (Plate 2, Figures 8 to 10.) 



The following is a description of this species: 



The zoarium is articulated. The segments are formed of two longitudinal 

 rows of zocecia placed only on one side of the zoarium. The zocecia are dis- 

 tinct, club-shaped, with long, convex, and porous gymnocyst. The mural 

 rim is thin and granular. The opesium is elliptical, elongate, surrounded by 

 a salient rim; the two condyles are large and median. The cryptocyst is deep, 

 smooth, and small. 



Measurements. — Opesium: ho =0.14 mm., Zo=0.10 mm.; zocecium: Lz= 0.50 

 mm., te=0.20 to 0.22 mm. 



Affinities. — This species differs from Corynostylus labiatus in its 

 unilamellar segments with only two zocecial rows and in the absence of 

 a salient Up proximal to the opesium. Only the fragments figured have 

 been found; they are extremely fragile. 



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

 (Bluff 3), Santo Domingo. 



