210 ANNALS NEW YORK ACADEMY OF SCIENCES 



quadrate blocks when seen in longitudinal section. The inferior hemisepta 

 have not been observed. Tangential sections show the cells to be circular 

 or slightly elongated and arranged rather regularly in quincunx, so as to 

 form oblique rows as well as longitudinal ones. About 7 cells occur longi- 

 tudinally in 2 mm. The wall^ are thick, those separating laterally adjacent 

 cells being about one half the width, and those separating longitudinally adja- 

 cent cells about one half the length of the cells. The central line of the walls 

 is occupied by a row of spinules outlining a hexagon having perhaps 2 

 spinules to a side and one on each of the angles, although such an arrange- 

 ment is by no means constant. 



Idioclema gen. nov. 



The following description is based upon the only species known, and it 

 may therefore have to be modified when other related forms are brought 

 to light. The name Idioclema is then introduced for a Bryozoan type 

 having solid, straight, probably branching stems of small diameter. 

 There is a well-defined cortical zone in which the zooecia are radial and 

 have greatly thickened walls, and an inner or immature region in which 

 the zooecia have thin walls and for a long distance preserve a longitudinal 

 direction. On the interpretation of structure adopted here, mesopores 

 are absent, but acanthopores of abnormal tj^e are abundant. In fact it 

 would appear that the cortical zone, in which alone these structures 

 occur, was dominated by them and that they formed the walls by which 

 the irregularly oval or even tortuous zooecial tubes are separated, by 

 becoming confluent with one another as they come in contact. Each 

 acanthopore is as thick as the entire wall, and by uniting laterally they 

 form inosculating bands. The constituent unit can often be made out as 

 (in tangential section) large circular bodies having a tubular axis and 

 a row of elongated granules about the margin. The granules are perhaps 

 oblique inosculating fibers and show conspicuously when the tubes are 

 cut longitudinally. They appear to be irregular in direction and do not 

 make continuous lines for any considerable distance. Tabulae appear to 

 be absent. Hemisepta are, however, developed just within the cortical 

 zone. One projects upward and somewhat obliquely inward from the 

 proximal portion of the wall at the commencement of the thickened zone 

 and about at the point at which the tubes turn into a radial direction. 

 A second projects upward and somewhat obliquely outward from the 

 opposite wall a little farther down the tube. 



The affinities of the form are very much in doubt by reason of the 

 very unusual character of the wall structure. The presence of hemisepta, 

 however, is a diagnostic character and seems to forbid placing the genus 

 with the Batostomellidae, to which it shows some points of resemblance. 



