GIRTY, NEW CARBONIFEROUS FOSSILS 197 



large cavities are left between the contorted layers. The different sheets are 

 seldom over 2 mm. thick. 



The zooeeial walls are much thickened, but areas in which this feature is 

 developed occur adjacent to others in which the walls are thin. When the 

 walls are thick, the zooecia are more or less circular ; when thin, they are 

 more or less angular. They are rather irregular in size and shape. Maculae 

 composed of groups of larger or smaller cells seem to be present, but the dif- 

 ference in size is not great nor are the areas well defined so far as observed. 

 The thickening of the walls is accomplished by means of strong swellings 

 close together or more or less confluent. Typical acanthopores rare or pos- 

 sibly absent. The thickened walls, however, show a strong median line, iu 

 some sections appearing as a row of granules, often with a group of granules 

 at the cell angles. The median line is usually observable even where the 

 walls are thin, and it can also be made out in longitudinal sections. About 

 6 cells occur in 2 mm. The larger ones are from .28 to .35 mm. in diameter 

 (measured from the median line of the thickened walls). Mesopores (young 

 cells ?) fairly alnmdant. Diaphragms scantily developed. In some sections, 

 they seem to be absent ; in others, one or two occur in each cell. 



Stenopora miseri var. tubulata var. nov. 



This form resembles S. m,iseri in most of its characters, differing only 

 in the degree in which they are developed. The acanthopores are more 

 numerous, most of the cell angles being occupied by them, but they are 

 for the most part small, not indenting the zooecia. The thin-walled 

 areas are more extensive than in the other. When thickened, the walls 

 usually show a distinct median line and they are marked by fine granules, 

 varying in quantity in different parts of the zoarium. The diaphragms 

 are rather abundant and closely arranged, usually less than a diameter 

 apart. Groups of large cells occur such that only fi.ve or even four are 

 found in 2 mm. 



Stenopora simulans sp. nov. 



This species, in its mode of growth, is like S. mutahilis, forming extremely 

 irregular bodies partly ramose, partly explanate or massive, and apparently 

 more or less confluent. The branches are small, 5 mm. in diameter. 



The walls vary from thick to thin, in some places changing rather abruptly, 

 and while this may be due in part to the irregularity of growth, in part it 

 must doubtless be assigned to variation at the same stage of development. 

 The cells vary from subcircular to more or less strongly polygonal and occur 

 about G in 2 mm. Mesopores are rare. Normal acanthopores (with concen- 

 tric structure) appear to be absent. At the same tim^, the walls are beset 

 with large acanthopore-like granules, many of which seem to have a tubular 

 axis about which little dots of denser material are assembled. Where the 

 walls are thick, the dots are more spread out, and where the walls are thin. 

 they are more concentrated. Where the walls are thin. also, the granules 

 sometimes indent the cells. Similar and not conspicuously larger granules 

 occur at the cell angles. The granules are developed in the thin as well as 



