226 Systematic Paleontology 



tended sections cut the frequent monticules at all angles and appear like 

 panels of curly maple. 



" In specimens which break along the latilaminge the surface is seen to 

 be vermiculate and porous, thickly covered with prominent conical ele- 

 vations. This characteristic vermiculate structure is shown also . in 

 tangential sections, and is not due to weathering and preservation. As- 

 trorhizse are numerous, but small and inconspicuous, as if they were merely 

 the usual porous structure intensified. They are . distributed over the 

 surface, and are often to be found on the sides of the monticules. The 

 monticules, as shown by radial section, are usually superimposed through- 

 out one latilamina, but in two consecutive latilamina? this may or may not 

 be the case. They are often pierced by straight central canals directed 

 radially. These canals often extend through one whole set of monticules. 

 They have no proper walls, and, therefore, cannot be referred to ' Cauno- 

 pora ' tubes or tubicolous annelids. When broken transversely the mame- 

 lons are seen to be distinctly porous. The pores, or canals, are often 

 arranged in concentric series, coincident with the cut edges of the inter- 

 sected laminae, and evidently represent sections of the astrorhizal canals. 



" Weathered fractures and properly oriented sections show that the radial 

 pillars are strong, parallel, and continuous through several layers of the 

 ccenosteum. They are united at more or less regular intervals by con- 

 centric partitions which have the porous structure above described. These 

 concentric laminae appear to be composed of inosculating fibers forming 

 a reticulate skeleton, and not of lateral arms given off in a whorl around 

 each pillar as in the genus Actinostroma. ■ Vertical sections through a 

 monticule show that the radial pillars are not parallel as elsewhere, but 

 are inclined at a slight angle away from the imaginary axis of the monti- 

 cule." Girty, 1894. 



The monticules are elevated, conical, about 3 to 3| mm. apart. Eadial 

 sections show thin horizontal laminae about 3 of which occur in 1 mm.; 

 vertical pillars about 7 in 1 mm. The laminae curve strongly upwards in 

 passing through the monticules. Tangential sections show groups of 

 concentric circles which are sections of monticules ; monticules pierced by 

 axial tubes ; astrorhizae scarcely distinguishable, sections of vertical pillars 

 irregular in shape. 



