The Relationship of the Tetracoralla to the Hexacoralla. 169 



of the base. Corallites small, polygonal, contracted inferiorly 

 so as to become funnel-shaped. Septa represented by faint mar- 

 ginal ridges, or obsolete. Walls pierced by irregularly distrib- 

 uted mural pores ; tabulae sparse." 



List of Species. 



Pleurodictyum prohlematicum Goldfuss. Genotype. 

 Petrif. Germ., Vol. I, 1826: 113. 



Locality and horizon: Western Europe. Middle Devonian 

 (EifeUan). 

 Pleurodictyum stylopora Eaton. 

 Geol. Text-book, 1832 : 40, PI. 4. 



Locality and horizon: Western New York. Devonian (Ham- 

 ilton). 

 Pleurodictyum lonsdalei Richter. 



Zeit. deutsch. geol. Gesell., Vol. VII, 1855 : 559-565. 

 Locality and horizon: Near Saalfeld, Thiiringen, Germany. 

 Devonian. 

 Pleurodictyum{f) selcanum Giebel. 



Silur. Fauna d. unt. Harzes, 1858 : 56, PI. 6. 

 Locality and horizon: Magdesprung and Zorge, Germany. 

 Lower Devonian (Hercynian). 

 Pleurodictyum Constantino politanum Roemer. 

 N. Jahrb. f. Min., etc., 1863 : 519, PL 5. 



Locality and horizon: Near Constantinople, Turkey. Devonian. 

 Pleurodictyum megastomum McCoy. 

 Ann. Mag. Nat. Hist., Ser. 3, Vol. XX, 1867 : 201. (Listed but 



not figured or described.) 

 Locality and horizon: Victoria, Australia. Silurian. 

 Pleurodictyum lenticular e (Hall). 



Michelinia lenticidare Plall. 26th Ann. Rep. N. Y. State Mus. 



Nat. Hist., 1873, 1874: 113. 

 Locality and horizon: New York. Devonian (Hamilton). 

 Pleurodictyum petrii Maurer(?). 



N. Jahrb. f. Min., etc., 1874:456, PL 7- 



Locality and horizon: Near Giessen, Germany. Lower Devo- 

 nian. 

 Pleurodictyum americanum Roemer. 



Leth. Geog., Pt. I, Leth. Pal., Atlas, 1876: PL 33- 



