206 



NEW YORK STATE MUSEUM 



Corematocladus densa sp. nov. 



Plate 3, figures 1-5 



The thallus is small, about 28 mm in diameter and 30+ mm long. 

 It consists of a thick central stem or stipe which most probably was 

 a cylindric branch, but possibly may also have been platelike and 

 attached to other bodies, thus representing- only the attachment 

 plate. Its surface is corticated, being covered with a pavement 

 of plates, some of which are distinctly ringlike [see pi. 3, fig. 4, 

 5]. These rings seem to have been the bases of the filamentous 

 branchlets which from their distinct preservation may also have 

 been strongly corticated. The latter bifurcate frequently, the 

 bifurcations apparently following each other more rapidly in the 

 distal portions and in some places they appear to be whorled, divid- 

 ing into three or probably four branchlets. There are six or more 

 bifurcations in each branchlet from the base to the extremity. The 

 branchlets diverge at small angles and become subparallel. They 

 appear rather rigid and become thinner with each bifurcation, the 

 basal portion reaching- about .3 mm in width, the distal portion 

 but .1 mm and less. They are seen to be furnished with trans- 

 verse walls that in the proximal portion are about twice as far 

 apart from each other as the branchlet is wide and that divide the 

 latter into squarish segments in the distal portion. Directly below 

 the bifurcations the continuity of the branchlet is frequently seen 

 to be interrupted and the segments are slightly inflated on both 

 sides ' of the line of interruption giving the impression of an 

 articulation. 



The systematic position of this small but striking form is at 

 present still very doubtful. The habitus is decidedly more that of 

 an alga than of either a graptolite or of a colonial stock of sertula- 

 rian or anthozoan affinities, although the strong and glossy carbona- 

 ceous test seems highly suggestive of the graptolite nature of the 

 fossil. The absence, however, of cell apertures on the multitude of 

 branchlets 1 and the distinctness of the transverse walls where the 

 test is broken through the middle (they do not show on the smooth 

 outside) are characters favoring a reference to the vegetable king- 

 dom. It must not be forgotten on the other hand that the main 

 axis or stipe might be the theciferous part, the ringlike bases of the 

 'branches, the apertures of thecae, while the branchlets themselves 

 were but filamentous processes of the thecae, the form being a Den- 



1 There were seen a few subcircular scars or openings on the test which 

 however are in the place of bifurcations and apparently are produced by 

 the breaking off of one of the branches at the articulation. 



