268 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



Richmond or closing age of the Ordovician, the last in the Keokuk 

 formation of the Mississippian series. 



In 1884, and again in 1887 (op. cit.), Vine described a Rhopalo- 

 naria hoteUus and thereby confused this and the other very different 

 species upon which we found the new generic group Allonema. In 

 1886^ Ulrich added to the confusion by describing a variety of Stoina- 

 topora delicatula James as Rhopalonaria pertemiis, an error that was 

 corrected in his later work on Minnesota Bryozoa. 



RHOPALONARIA VENOSA Ulrich 



(Plate LXVI, 2, 3) 

 1879. Rhopalonaria venosa Ulrich, Jour. Cin. Soc. Nat. Hist., 11, p. 26, 



pi. vii, 24, 24a. 

 1889. Rhopalonaria venosa Miller, North Amer. Geo), and Pal., p. 321, 



fig. 511- 

 1893. Rhopalonaria venosa Ulrich, Geol. Minnesota, in, p. 114, fig. 8c. 

 1897. Rhopalonaria venosa Simpson, Fourteenth Ann. Rep. State Geol. 

 New York for 1894, p. 603, fig. 221. 



Zoarium growing on various bodies — corals, brachiopods, and 

 shells of pelecypods. Cells distinctly swollen, fusiform, connected 

 by very slender stolons of an average length equaling that of the 

 cells, all arranged somewhat irregularly in a pinnate manner, an 

 average of 5 or 6 cells in the midrib in 3 mm. and the same number 

 in the lateral branches in 4 mm. Occasionally an arrangement simu- 

 lating the web of a spider may be observed in large colonies. Fusi- 

 form cells averaging o.i mm. or less in diameter and about 0.3 mm. 

 in length; many with a minute, elevated, eccentrically situated pore- 

 like spot. 



On account of the extreme simplicity of these fossils, we find it 

 difficult to draw up satisfactory descriptions. The size, form, and 

 arrangement of the cells and the relative average length of the con- 

 necting tubes are the points relied on in distinguishing the species. 

 In recognizing these the illustrations will doubtless prove of greater 

 service than descriptions, and the latter, therefore, will consist prin- 

 cipally of comparative remarks. 



Occurrence. — Richmond group, numerous localities in Ohio and 

 Indiana, The types are from Waynesville and Clarksville, Ohio. 



Cat. Nos, 43,111-43,115, U, S. N, M, 



RHOPALONARIA ATTENUATA new species 



(Plate LXVI, 4, 5) 

 In this species the length and arrangement of the internodes and 

 stolons is practically the same as in R. venosa, but its colonies are 

 ^Fourteenth Ann. Rep. Geol. Nat. Hist. Snrv. Minn., p. 59. 



