149 



Itatostoma vaiiabile (pars). Ulricli, Geol. Surv. 111., Vol. VIII, 1S90, p. 



460, pi. XXXV, Figs. 4b, 4c (non 4, 4a, 5, or pi. xxxvi, Fig. 1). 

 Slonticulipora varians. J. F. James, Jour. Gin. Soc. Nat. Hist., A^ol. XVI, 



1894, p. 199. 

 Batostoma variahUc. J. F. James, Jour. Gin. Soc. Nat. Hist., Vol. XVI, 



1S94, p. 200. 

 Batostoma varians. Nickles and Bassler, Bull. U. S. Geol. Surv., No. 173, 



1900, p. 179. 

 Batostoma varians. Nickles, Kentucky Geol. Surv., Bull. No. 5, 1905, p 



57, pi. iii, Figs. 8, 9. 

 Batostoma varians. Bas.sler, Proc. U. S. National Museum, Vol. XXX. 



1906, p. 18. 

 Batostoma varians. Cumiugs, Indiana Dept. Geol. Nat. Res. 32d Ann. 



Kept, 1907, p. 77S, pi. vii. Fig. 9; pi. viii, Figs. 3-3b; pi. xxvi, Fig. 



14. 



Zoarium irregularly ramose, branches .5 to 10 mm. in diameter, 10 to 

 SO mm. long; subfrondescent, or encrusting on the shells of brachiopods. 

 Orthoceras, or other bryozoa. The encrusting forms are from one to 5 mm. 

 thick, and frequently cover an area of 20 to CO sq. cm. Cylindrical branches 

 £i.nd knobs may spring from any portion of the zoarium. Surface smooth. 

 GO monticules, and only an occasional macula of larger zooecia and meso- 

 pores. On unweathered specimens the knob-like projections of the acan- 

 thopores appear at the angles between the zocecia. The pores at the ends 

 of the acanthopores are funnel-shaped. The zocecia, at the surface are 

 usually angular or oval, sometimes rounded, and vary much in size and 

 the thickness of the walls. The thin-walled zooecia are angular, and the 

 thick-walled ones are round or oval. Mesopores fewer than the zooecia, 

 at the angles of the latter, and in the macular; sometimes long and nar- 

 row, separating the zooecia in thick-walled specimens. 6 or 7 zooecia in 

 2 mm. 



The tangential section shows the zooecia to be thick-walled and sep- 

 arated by a conspicuous median lamina. Zoopcial apertures oval, meso- 

 pores fairly abundant, not so numerous as the zooecia. Acanthopores abun- 

 dant, situated at almost every angle between the zooecia, rather large, thin- 

 walled with wide central canal. Acanthopores sometimes occur in the 

 wall between two zoa-cia and then slightly indent the wall. Communica- 

 tion pores abundant in some specimens, but usually absent In very shal- 



