BRYOSOA. 411 



the zooecia, sometimes found in the axial region; now and then 

 they do not follow the trend of the zooecia in the cortical re- 

 gion, but cut across the tubes at an acute angle. The acantho- 

 pores found in the maculae are longer and larger than the 

 others. In some parts of a longitudinal section, the acantho- 

 pores are seen to have exceedingly thin cross partitions. 



The elongated dimples distinguish this species from all other 

 described forms of the genus. An undescribed related form, oc- 

 curring in the Cincinnati group, at Waynesville, Ohio, also has 

 somewhat similar elongated dimples, but differs in other char- 

 acters. 



Position and locality: Cincinnati group, Wilmington, 111. 



HOMOTRYPA FLABELLARIS UMch. 

 PI. XXXII, flg. 3-3c 



Zoarium consisting typically of fan-shaped fronds; an almost 

 perfect specimen gives the following measurements: width 45 

 mm., height 50 mm., thickness 5 mm. Surface smooth, with 

 obscure maculae about four mm. apart, measuring from center 

 to center. Peripheral portion of zoarium narrow. Walls of 

 zooecial tubes flexuous or crenulated in the axial region, 

 and very thin even in the cortical region. Zooecia apertures 

 angular, slightly oblique, from eight to ten in two mm., those 

 in the maculae from a third to a half larger than the average. 

 Mesopores few, gathered into clusters in the maculae. Zooecial 

 tubes provided with a few remote straight diaphragms in the 

 axial region. Diaphragms moderately numerous in the meso- 

 pores. Cystiphragms form a short series in each tube. Acan- 

 thopores few, very small. 



A very close variety occurs in the upper beds of the Cincin- 

 nati group, at Blanchester, Ohio, which has the maculae a little 

 more pronounced, and a tendency to a ramose growth. The 

 thin walls and flabellate growth distinguish H. tiabellaris from 

 the hitherto described species of the genus. 



Position and locality: Cincinnati group, Wilmington, 111. 



