24 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxx. 



and ill contact at the surface because of the scarcity of mesopores in 

 this region. The zocecial characters of variety siglUarioides are the 

 same as in the tN'pical form, but the zoarium differs in consisting- of 

 rather long, graceful branches, 4 or 5 mm. in diameter, dividing less 

 frequently and not tending to anastomose. 



The internal structure of C. onealli is essentially the same as that 

 figured b}" Nicholson in 1881'* for the variety sigillarioides, but tangen- 

 tial sections of variety co//i//i i/nis differ from both in showing few meso- 

 pores and polygonal zooecia. 



Occur /'f}ice. — C. onealJl is particularly abundant in the Econoni}'' 

 member of the Eden shale in the vicinity of Cincinnati; variety sigil- 

 larioides ranges through the formation in equal abundance while 

 variety coiiuinuitti is best developed in the upper (McMicken) member 

 of these rocks. 



CALLOPORA ONEALLI COMMUNIS (James). 



Plate 1, fi^. 13; plate IV, figs. 8, 9. 



Monticulipora {Heierotrt/pa) onealli'! var. coHiHuai/.s James, Paleontologist, No. 6, 



1882, p. 47; No. 7, 1883, pi. i, fig. 8. 

 Monticnlipom communis James and James, Jour. Cincinnati Soc. Nat. Hist., X, 



1888, p. 175, pi. II, figs. 5a, b. — J. F. James, Jour. Cincinnati 8oc. Nat. Hist., 



XVI, 1894, p. 195. 

 (alloporaonealli-commimis Nickles and Bassi.er, Bull. IT. S. Geol. .Surv., No. 173, 



1900, p. 190. 



This variety has been discussed in the remarks under Oallopora 

 onealli and, as there stated, may be distinguished from the typical 

 form of the species by its decided h' robust instead of delicate branches 

 and ))}• its few mesopores. The branches are usually about 7 mm. in 

 diameter and form bushy masses by their anastomosis. The internal 

 structure is the same as in C. onealli and var. mjUlarloides with the 

 exception that as the surface is approached many of the mesopores 

 pinch out so that at the surface itself the zocecia are in contact prac- 

 tically on all sides. This causes the zocpcia to assume a polygonal 

 outline and to become a trifle larger than in typical C oneallL Thej'^ 

 are also larger than in the variet}'^ siglUarioides^ but the average 

 number of zocecia in a given space is the same in all three forms. 



The types of the variety com munis are missing, but the examples 

 here figured on Plate IV are identical with specimens labeled by Mr. 

 James in the collections of the U. S. National Museum. 



Occurrence. — Abundant in the Eden shale at manv localities in the 

 Ohio Basin, Cincinnati being the tj'^pe locality. Especially tine speci- 

 mens are found in the upper beds of this formation. 



"(u'nus Monticulipora, 1881, p. 118, pi. iii, figs. .3-3f. 



