134 BULLETIN OF THE LABORATORIES 



ridges strongly marked ; we do not however know whether it belongs 

 to the first or third types. 



In 1866 Mr. Rudolph Ludwig in Cor. aus Pal. Form, divided 

 Pleurodictyum into two genera, giving each a new name, thus prac- 

 tically abolishing this genus. Ptchychochartocyclus contains those 

 forms in which the interior walls of the polyp have longitudinal ridges, 

 and these ridges are beset with distinct tubercles. Taeniochartocyclus 

 contains those forms in which the ridges are not beset with tubercles 

 but are smooth. They correspond to the first and third types of 

 Edwards and Haime. 



In Kentucky Fossil Corals, Mr. William J. Davis figures a new 

 genus, Procteria. The figures seem to indicate the existence of mural 

 pores connecting the polyps and also of tubercles ornamenting its 

 interior. An examination of numerous specimens show that the 

 character of the ridges is extremely variable in both tuberculated and 

 nontuberculated forms, and that they are often absent. At any rate 

 we do not find in the figure of Pz-^r/^r/^ any thing to distinguish it 

 from Ptchychochartocyclus, and this is only a synonym of Pleurodictyum 

 even if it be indeed considered necessary to subdivide the genus. It 

 will be therefore a matter of interest to learn what the forthcoming 

 text may have to offer on that subject. 



Forms have been referred to Pleurodictyum problematicum from 

 various localities in North America and with a range from the Onon- 

 daga Group of New York to that of the Waverly Group in Ohio. We 

 believe that on study these would be found to belong, to several dis- 

 tinct species. Notwithstanding this range, the large celled forms of 

 corals which pass under the name of Pleurodictyum are usually typical 

 of Devonian strata, and are found there most frequently. 



Pleurodictyum has been identified by Rominger and Lindstroem 

 with Favosites and Michelinia. The type of the genus is more of the 

 character of Michelinia. It seems to us therefore that Pleurodictyum 

 has precedence over Michelinia. It contains ty[)ically the species of 

 Goldfuss, the first type of Edwards and Haime, Ptchychochai'tocyclus 

 stigmosus, Ludwig, and apparently the Procteria of Davis. If it be 

 considered admissable to separate the forms without the tubercles, 

 Ludwig's genus laeniochartocyclus has the precedence. 



We prefer also to retain the name Pleurodictyum for the Austra- 

 lian form in particular, because the vesiculose tissue of Michelinia has 

 not as yet been seen in Australian specimens. For a discussion of the 



