ii8 Carl O. Dunhar, 



pores occupies a distance of 7 mm. to 7.4 mm. Tabulae some- 

 what irregularly arranged, eight to twelve in a distance of 10 

 mm. 



Dimensions: An average specimen measures 50 mm. in diam- 

 eter and 25 mm. in height, but there is much variation in size, the 

 largest specimen being 85 mm. in diameter. 



Discussion: The convex base and horizontal corallites of this 

 species contrast strongly with the flat base and ascending coral- 

 lites of F. conicus, with which it is associated. It most closely 

 resembles the mid-Devonian F. hemisphericus, but that species 

 is much larger, has a more pointed and decidedly excentric apex 

 to its base. 



Occurrence: Common in the Birdsong shale and Ross lime- 

 stone at localities on Birdsong and Lick creeks, at Perryville, 

 Grandview, Pyburns, etc. 



Name: The form is named after Doctor August F. Foerste, 

 who recognized it as a distinct species but did not describe or 

 name it.^ 



Pleurodictyum trifoliatum, n. sp. 

 Plate I, figs. 5-7 



Description: Small trifoliate corallum, composed of three 

 shallow cup-shaped corallites. The corallites are subcircular on 

 their free sides but are flattened slightly where they are con- 

 tiguous. Externally they are covered by a wrinkled epitheca. 

 Internally the wall of each corallite is marked by about thirty 

 strongly granulose longitudinal ridges, and the bottom of each 

 cup is irregularly granulose. The common wall between con- 

 tiguous corallites is irregularly perforated by communicating 

 mural pores. The colony almost invariably consists of three 

 corallites, though a few have been found with only two, and one 

 specimen has but one; there is also a single instance of a colony 

 with five corallites. 



Dimensions: Diameter of a corallite, 5-6 mm. ; height, 3-5 mm. 



Discussion: The development of this simple colony is readily 

 made out, and it agrees exactly with that determined by Beecher^ 



I 



^The Silurian and Devonian limestones of western Tennessee. Jour. 

 Geology, vol. 11, 1903, p. 714. 



"Beecher, C. E., The development of a Paleozoic poriferous coral. 

 Trans. Conn. Acad. Arts Sci., vol. 8, 1891, pp. 207-212. 



