BRYOZOA. 443 



the average. Zooecial apertures angular or sub-circular, fre- 

 quently preserving the perforated opercula. separated by thin 

 interspaces, about nine or ten in three min. Zooecial tubes pro- 

 ceeding in a very gradual curve to the surface where they are 

 almost direct. Walls of zocecia very thin and flexuous in the 

 axial region, considerably thickened in the peripheral region 

 where they are more or less regularly moniliform, the swellings, 

 however, not separated by very thin intervals. Divisional line 

 between adjoining zocecia generally well defined. Diaphragms 

 horizontal, with a sub-central perforation, having a thickened 

 margin, rather more than one-half their diameter apart, devel- 

 oped mainly in the cortical region. Mesopores oval, very few. 

 Acanthopores of moderate size, situated generally at the angles, 

 occasionally projecting into the zooecial cavity. 



Sections of a single example show what may be rather large 

 communication pores. In tangential sections the}' appear as 

 simple transverse lines of lighter color than the walls. In ver- 

 tical sections they are again represented by narrow light inter- 

 vals, traversing the walls in a direction parallel with the A- 

 shaped layers of sclerenchyma. 



Position and locality: Chester group. Common at Sloan's 

 Valley. Pulaski Co.. and other localities in Kentucky. Several 

 illy preserved specimens from Chester, Illinois, are supposed to 

 belong here. 



*.- 



STENOPORA MEEKANA Ulrich. 



PL LXXm, Fig. 7-7a. 



Zoarium ramose, consisting of robust branches, fifteen mm. or 

 more in diameter. Surface without monticules but marked with 

 clusters of cell apertures about one-third larger than the aver, 

 age size. Apertures angular, with thin interspaces, about nine 

 of the ordinary size in three mm. Zooecial tubes curving gradu- 

 ally from the axial region, direct in the peripheral region. 

 Walls thin and irregularly flexuous in the axial region, thick- 

 ened and more or less moniliform in the cortical region. Divi- 

 sional plane between adjoining zooecia, marked by lighter colored 

 tissue or a dark line. A few thin diaphragms are developed as 

 the tubes approach the mature region. Here[they are somewhat 

 thicker, and <] about two-thirds of a tube diameter 



