BRYOZOA. 511 



EVACTINOPORA GRANDis Meek and Worthen. 



PI. LXXHI, fig. 4. 

 Evactinopora grandis M. & W. 1868. Geol. Surv. of 111. vol. Ill, p. 503. PL XV.flg. 2a, 26. 



This species, like E. quinqueradiata, has very much larger 

 rays than the other species. They attain in the largest examples 

 a width of eight cm., but in a small specimen before me, they 

 are only four cm. wide. Their entire height has not been ob- 

 served, but I do not think it was as great as the width; their 

 greatest thickness varies from 4 to 8 mm., and the taper to 

 the outer extremity is very gradual. Far up, the axis is rhom- 

 bic in shape, and the rays are very much contracted immedi- 

 ately after leaving the axis. The rays are four in number, ex- 

 tending out at right angles to one another. Zooecial tubes 

 oblique, the apertures small, round, regularly arranged in quin- 

 cunx, separated by interspaces about equal to t\vice their di- 

 ameter; five or six in three mm.; interspaces filled with vesicu- 

 lar tissue, the vesicles open except near the surface, where they 

 are as usually filled with a deposit of sclerenchyma. 



There are several peculiarities in the minute structure, but 

 the preservation of the Bryozoa in the Burlington limestone is 

 rarely so satisfactory that they can be determined. 



Luckily the basal portion of the zoarium usually holds to- 

 gether, so that the three species found in this rock can be dis- 

 tinguished by the number and form of the rays. 



Position and locality: Burlington limestone, Burlington, Iowa. 



GLYPTOPORA Ulrich, 1884. 



(Jour. Cin. Soc. Nat. Hist VoL VII, p. 39.) 

 (For generic diagnosis see page 387.) 



During the preparation of this work I have had an abundance 

 of material for study, and in many instances I have been en- 

 abled to give a better definition of genera previously proposed 

 by me. This genus required perhaps more time than any other 

 to master fully. The principal difficulty was encountered in the 

 determination of the method of growth of such forms as G. 

 keyserlingi and G. punctipora. The fragmentary remains, 



