198 ANNALS NEW YORK ACADEMY OF SCIENCES 



the thick walls, althonsh they are less numerous in the former. Even where 

 the walls are more attenuated, however, a few can occasionally be distin- 

 siuishecl. The mature zone is long and the walls as a rule continuously thick- 

 ened, though in varying degree. Here and there the characteristic moniliform 

 structure is shown or suggested. Diaphragms are fairly abundant and very 

 irregularly distributed, varying from one half to 2 or more diameters apart. 



Stenopora mutabilis sp. nov. 



Zoarium in the type specimen in form of a slender cylindrical branch a 

 little less than o mm. in diameter, but assuming in other specimens a very 

 irregular growth, partl.v explanate, partly more massive, ver.v much contorted 

 and sending up from its base short (?) branches of varying size, b\it probably 

 always small, which appear to inosculate with one another and with the rest 

 of the zoarium. when the irregular mode of growth brings them in contact. 



Zooecia small, rounded, about 9 in 2 mm., varying considerably in size, but 

 without conspicuous groups forming maculre. Walls usuall.v thick, measuring 

 about one half the diameter of the zooecia, thin in the central portion, but 

 with a very long mature region. At the same time, the walls vary greatly 

 in thickness (in tangential section) within very short distances and are in 

 places almost linear, in which case, of course, the cells are pol.vgonal. Owing 

 to the very irregular, contorted growth of this form, the variation in the 

 thickness of the walls may sometimes be due to varying distances from 

 the immature region. The thickening of the walls is continuous and not 

 beaded. Mesopores (young cells ?) rather rare and in the preservation of 

 my specimens difficult to distinguish from acanthopores. Acanthopores ex- 

 tremely large, in some cases about one half the diameter of the cells, which 

 they strongly Indent, except when the walls are thick. Diajihragms numerous 

 and irregularl.v arranged, from one half to rather more than a diameter apart, 

 somewhat doubtfully perforated. 



Stenopora ramosa var. fayettevillensis var. nov. 



Zoarium consisting of rather slender, solid, cylindrical stems about 5 mm. 

 in diameter. Zooecia vertical in the median region, rather gradually bending 

 outward to the circumference, onl.v a short portion, however, having a radial 

 direction. Five or 6 apertures occur in 2 mm. Mesopores moderately abun- 

 dant for the genus, occurring singly or in groups, associated with cells larger 

 than the ordinarv. Zooecia and mesopores polygonal with rounded angles. 

 Walls moderately thickened in the mature region, which is narrow, two or 

 three times the diameter of the larger cells. The thickenings are continuous, 

 but swollen and irregular. The division lines in the walls' are well defined, 

 in places intermittent or granulose. Acanthopores are of moderate size and 

 abundance occupying nearly all the angles, but not indenting the zooecia. 

 Tabul.Tp are rather abundant in the narrow cortical zone to which they are 

 perhaps restricted ; from one half to one cell diameter or more apart. 



Stenopora gracilis sp. nov. 



Zoarium ramose, consisting of solid branches which have a diameter of 

 5 mm. or more. The zooecial tubes run lengthwise in the axial region and 



