1 8 LOWER PENINSULA. 



HOUGIITONIA. 



N. Gen. 



Tubes circular, with projecting rims ; cavity lined by twenty 

 or more longitudinal crests, and transversely septate by subplane 

 diaphragms. Coenenchym formed of irregularly lacunose cell spaces 

 anastomosing amongst themselves, and frequently by pores with 

 the tube channels. Intertubular interstices narrow — the tubes are 

 often in immediate contiguity, so that the intertubular coenenchym 

 becomes restricted to the corners left between the joining tubes. 

 No pore communication between the contiguous tube walls. 



HOUGHTONIA HURONICA, N. Sp. 



Globular masses, from the size of a man's fist to that of a foot in 

 diameter, with a basal scar of attachment. Tubes from two to 

 three millimeters in diameter. Interstitial spaces narrow, or tubes 

 in partial immediate contiguity without intervention of coenenchym 

 cells. Vertical crests spinulose. Diaphragms numerous, slightly 

 concave, and usually coincident with linear constrictions of the 

 tubes. By intersection of the vertical crests with these constricted 

 annular rims, the inner surface of the tubes becomes cancellated by 

 regular, square-shaped conical pits, the bottom of which is often, 

 but not always, perforated, and communicates with the cell spaces 

 of the surrounding coenenchym. 



Occurs in the Hudson River group of Drummond's Island, 

 associated with Columnaria stellata. It is likewise 7ound abun- 

 dantly in the upper part of the Cincinnati group at Madison, 

 Indiana ; more rarely in the lower strata of the same locality. 



Plate III. — Fig. 3 is a lateral view of a specimen from Drum- 

 mond's Island, split open. Fig. 4 is a surface view of the same. 



Note. — Since the above was written, I have noticed in the second palseontologi- 

 cal report of Ohio the description of Columnopora cribriforviis, which is generically 

 identical with Hozightonia, but Mr. Nicholson erroneously asserts the absence of 

 intertubular coenenchym cells, and thinks the tubes directly anastomosing by large 

 lateral pores. This is not the case in tubes contiguous to each other, where 

 the walls are imperforate ; but in case of development of intermediate coenenchym 

 cells the tubes connect by pores with the coenenchym, and in this way indirectly 

 with each other. 



