1886.] NATURAL SCIENCES OP I'HILADELPHIA. 56 



These numerous processes vertically intersecting the inter- 

 lamellar spaces increase the resemblance of these fossils to 

 Sti'omatopora. Each of the undulating superimposed laminae, 

 of not quite one millimetre in thickness, and about from one to 

 three millimetres distant from one another, is composed of a 

 layer of horizontally prostrate tubules with solid intimately 

 united walls, which after some extent in the horizontal position, 

 abruptly bend upward and open on the surface of the laminae 

 with oblique compressed orifices bordered on the outside either 

 by a sharp lip, or by a vertically rising strong proboscidal pro- 

 longation, similar to the pillars on the surface of the lamellae of 

 a Stromatopora. The underside of each one of these lamellae in 

 the concentric succession, is covered by a wrinkled epithecal 

 crust, through which the outlines of the single tubules compos- 

 ing the lamella are plainly visible, just as we see it on the under- 

 side of foliaceous expansions of Alveolites, and indeed, the 

 structure of this fossil in every respect corresponds with the 

 structure of Alveolites or Limai'ia, and has no analogy whatever 

 with Stromatopora. 



As the numerous specimens I possess of this fossil were not 

 only found in the same locality from which Prof. Nicholson's 

 type specimen comes, but were collected at the same time when 

 Rev. Mr. Herzer picked up the specimen now in possession of 

 Prof. Orton, of Ohio, I am positive that the objects I have under 

 consideration are identical with Prof. Nicholson's type specimen. 

 A very similar concentrically laminated fossil, but on the 

 whole of coarser structure, with interlaminar spaces from three 

 to five millimetres in width and with very stout intervening 

 pillars is not rare in the drift deposits of Ann Arbor. The 

 specimens are silicified and the structure of tlie lamime, as 

 being composed of a layer of prostrate tubules, is no longer 

 recognizable. The wrinkled epithecal crust on the underside of 

 each lamina is, however, still well preserved. The pillars, if 

 broken through, exhibit sometimes a central channel ; the shorter 

 ones, not injured, are imperforate at the apex ; some of the larger 

 pillars divide into mammiform side branches. There remains 

 no doubt in my mind that this and the former Dictyostroma of 

 Nicholson belong to the tribe of Alveolites^ Limaria, etc. I pro- 

 pose, therefore, for them the name of Alveolites stromatoporoides. 

 A genuine Stromatoporoid which in its external aspect has 



