GIRTY, yEW CARBONIFEROUS FOSSILS 211 



While forced to conclude that Idiodema cannot rightly be referred to 

 the Batostomellidfe, I am none the less in doubt as to ^vhere it should 

 properly be placed. Provisionally I am including it in the Ehabdome- 

 sidff. It may form the nucleus for an independent family, the Idio- 

 clematidge. 



Type. — Idiodema insigne. 



Idioclema insigne sp. nov. 



Zoarium in the form of freely branching stems, more or less circular in 

 cross section, but expanded and compressed at points of bifurcation. Diam- 

 eter ranging to 5 mm., usually less, and averaging about 3 mm. Superficial 

 characters not known. 



Cortical zone strongly marked and very variable in thickness, probably 

 according to age, ranging from one third to one sixth of the diameter of the 

 stem on each side. Zooecial tubes long and straight in the axial region where 

 they are .008 to .14 mm. in diameter, then slightly inclined to the surface and 

 later abruptly turned to a radial direction. Diaphragms appear to be want- 

 ing, but hemisepta are well developed. There occurs an incomplete partition 

 projecting inward and upward from the lower wall of each tube just as it 

 turns into an axial direction. A second incomplete partition projecting- 

 obliquely upward and outward frequently occurs a little farther down the 

 tube on the opposite wall, where it has a slightly inclined direction. 



The structure of the walls is difficult to describe, and the terms used depend 

 largely upon whether the appearances in section are interpreted as much 

 modified acanthopores with large tubular axes or as mesopores without true 

 acanthopores. The walls are thin in the axial region and strongly and 

 abruptly thickened in the cortical zone. In tangential section, the zoarium 

 appears to consist of tortuous, inosculating bands which leave between them 

 the openings for the zooeeia. The bands, representing the walls, seem to main- 

 tain a rather regular width, but the tubes between are irregular in size and 

 shape, subcircular, oval, or even more or less tortuous. The structure of the' 

 walls is peculiar. In places, they are represented by what may be considered! 

 very large abnormal acanthopores, having a circular shape in section and a 

 diameter about that of the entire wall. In the center is a relatively large 

 tubular axis and about the circumference a few fairly regularly arranged 

 granules which are slightly elongated and radially arranged. It appears to 

 be the fusing of these acanthopores (?) that produces the continuous walls, 

 which are intersected by similar granules, especially about the margins, niid 

 have distributed dowu the centers a row of similar axial tubes. When the 

 zooeeia are cut longitudinally, the structure of the cortical zone appears to be 

 more regular, consisting of the tubular cavities of the zooeeia alternating with 

 bands of varying width representing the walls and separable into units by the 

 tubules of the acanthopores. These large straight persistent tubular axes 

 are a striking feature, and there are in addition granules like those of the 

 tangential section, circular or elongated and either without conspicuous agree- 

 ment in direction or directed more or less obliquely downward toward the 

 tubular axis, showing that, if they are continuous fibers, the granules must 

 run irregularly through the acanthopore-like mass. 



