732 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
The zoarium is never exactly cylindrical and claviform fronds are not rare. 
The zoarial base is a little hook and not a calcareous basal expansion. 
Affinities .- — This species differs from Mecynoecia lunata in its thinner branches 
with 8 rows of tubes instead of 12, and in its smaller peristome (0.12 and not 
0.16 mm.). It differs from Mecynoecia elongatotuba ; in 8 rows of tubes instead 
of 6, and in its generally much smaller distance between the peristomes (0.90 and 
not 1.20 mm.), and from Entalophora pulchella Reuss, 1847, in its longer peristomie. 
Occurrence . — Vicksburgian (Marianna limestone) : West bank of Conecuh 
River, Escambia County, Alabama (very common) : Salt Mountain, 5 miles south 
of Jackson, Alabama (rare) ; Murder Creek, east of Castlebury, Conecuh County, 
Alabama (rare) ; deep well, Escambia County, Alabama (rare) ; 1 mile north of 
Monroeville, Alabama (very common). 
Vicksburgian (Red Bluff clay) : One-fourth of a mile of Woodwards, Wayne 
County, Mississippi (rare). 
Cotypes. — -Cat. Nos. 15394, 65395, U.S.N.M. 
MECYNOECIA ELONGATOTUBA, new species. 
Plate 155, figs. 23-29. 
Description . — The zoarium is a cylindrical and bifurcated Entalophora with 
six longitudinal rows of zooecia. The tubes are distinct, convex, very long , striated 
transversally, bent upward at their extremity and terminated by a short very 
oblique peristomie; the peristome is thin, orbicular, oblique. 
Diameter of peristome 0.12 mm. 
Distance between the peristomes 0.90-1.20 mm. 
Separation of the peristomes 0.44—0.50 mm. 
Diameter of the branches 0.90 mm. 
M easurements . — 
Y aviations . — The length of the tubes is very characteristic but it is not con- 
stant; on certain branches it is only 0.80 mm.; it is never more than 1.20 mm. The 
branches are never exactly cylindrical ; their base is often narrowed. 
The ovicell and the base are unknown. 
Affinities . — This species differs from Mecynoecia semota , of which the diame- 
ter of the peristome is identical in its thinner branches with six rows of zooecia 
instead of eight and in the long distance between the peristomes — almost always 
greater than 0.90 mm. 
It differs from Mecynoecia parvituba , of which it has a little the general 
aspect, in its larger peristomial diameter (0.12 and never 0.10 mm.). 
Occurrence . — Vicksburgian (Red Bluff clay) : Seven and one-half miles south- 
west of Bladen Springs, Alabama (common). 
Vicksburgian (Marianna limestone) : Murder Creek, east of Castlebury, 
Conecuh County, Alabama (very rare). 
Cotypes. — Cat. No. 65463, U.S.N.M. 
