570 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



ADEONELLOPSIS CYCLOPS, new species. 



Plate 100, figs. l-ll. 



Description. The zoarium is free, erect, bilamellar, formed of small clicho- 

 tomously branching fronds; the two lamellae, placed back to back, are inseparable. 

 The zooecia are distinct, elongated, elliptical, bordered by numerous parietal areolae. 

 The marginal zooecia are very long, and without distal avicularia on the peristome 

 or median avicularium and with a very small cribriform area. The median zooecia 

 are wide; their cribriform area is large and of little depth, and the median avicu- 

 larium is round and prominent. The peristomice is crescent shaped ; the peristome 

 thin and sharp, bears a small, round avicularium. The zooecia bear in their inferior 

 part one or two small adventitious avicularia. The old zooecia have thick walls 

 and their aperture, cribriform area and avicularia ai*e arranged at the bottom of 

 a total area. 



fZs=0.50-0.'56 mm. [A=0.06 mm. 



Measurements.-?^^ {^ =0 3(M) 32 mm Aperture(^ =0 ^ 15 mm 



Variations. On very young zooecia the parietal areolae are quite large (fig. 6) 

 but they are somewhat smaller on the others (fig. 3). 



The thickening of the pleurocyst is visible on figures 3, 4, 6, 8. When the 

 zooecia are old the total area occurs constantly. But in this species, this condition 

 is retarded and the normal zooecia are much greater in number than the old zooecia. 



At the base of the zoaria the zooecia, no longer having a polypide. have closed 

 apertures; only the avicularium and the areolae persist (fig. 7). The small peri- 

 stomal pore is absent in the marginal zooecia (fig. 3) and very small at the ends 

 of the fronds (fig. 6) ; but it is constant and rather large in the axial zooecia. 



On the old zooecia. which are much thickened (fig. 9). it disappears or is irregu- 

 larly placed. This pore, situated on the thin peristome and the rarity of the old 

 zooecia provided with a total area, characterize this species. 



The adventitious avicularia result from the coalescence of two or three areolar 

 cavities; they never have a pivot and are of the most simple type. 



Affinities. This species differs from AdeoneUopsis galeata in the occurrence 

 of the marginal zooecia different from the others and in its thin peristome. It may 

 be distinguished from Adeonellopsis magniporosa and from A. quisenberryae by 

 the presence of a small distal peristomial avicularium. 



Occurrence. Vicksburgian (Marianna limestone) : West bank Conecuh Biver, 

 Escambia County, Alabama (abundant) ; Murder Creek, east of Castlebury, Ala- 

 bama (abundant); near Claiborne. Alabama (abundant). 



Vicksburgian (Red Bluff clay) : Seven and one-half miles southwest of Bladon 

 Springs, Alabama (very rare). 



Vicksburgian (Byram marl) : Byram. Mississippi (very rare). 



Cotypes.C&t. No. 64321, U.S.N.M. 



