222 PAL^ONTOIiOGrY OF OHIO. 



series, Vol. XXII., p. 236) adds the following: " The tubes in the differ- 

 ent species vary from one quarter of a line to nearly one line in breadth ; 

 they are very long, and are most frequently united throughout laterally, 

 forming massive coralla resembling more or less those of Favosites and 

 Chsetetes ; sometimes, however, they are united in single intersecting 

 series, as in Halysites catenulata, Linn.; not unfrequently, too, the tubes 

 are isolated, or only united at irregular intervals, thus forming loose 

 fasciculated coralla resembling certain forms of Syringopora." 



Prof. Safford further states that the isolated tubes are nearly quadran- 

 gular, with more or less rounded angles, and with a slight external longi- 

 tudinal depression opposite to each of the four septa. The walls are 

 more or less rugose, and increase is by fission of the old tubes. Only one 

 specimen was seen in which the tabulae could be detected, and in this 

 they were confined to one end of the mass, and were distant from one 

 another about twice the width of the tubes. 



The genus is regarded by Safford as intermediate between the Favos- 

 itidx and the Rugosa, the quadripartite character of the corallites 

 placing it in the latter group. 



The material in my hands at present is insufficient for any further 

 elucidation of this singular genus, and I have nothing to add to the 

 characters above recorded, except that in most of the specimens I have 

 seen the tabulte appear to be present throughout the whole mass, and 

 can be made out without any difficulty. 



Of the four species enumerated by Safford from the Lower Silurian de- 

 posits, the Cincinnati group has yielded one form which I believe to be 

 Tetradium minus. 



Teteadium minus, Saiford, 



Tetradium minus, Safford; Amer. Jour. Sci. and Arts, 2d series, Vol. XXII., p. 238. 



Corallum massive, hemispherical, or amorphous, composed of slender 

 closely approximated corallites, which diverge from an imaginary axis. 

 The corallites are of great length, sometimes exceeding three inches, 

 with a width of from one-third to one-fourth of a line, their walls toler- 

 ably thick, and their shape irregularly four-sided or five-sided. The 

 septa are apparently four in each corallite, but they are imperfectly pre- 

 served, and can only be detected occasionally. There are, however, well 

 developed tabulae, which are complete and remote, from five to six usually 

 occupying the space of one line. 



I do not know if the specimens from which I have taken the above 



