528 PALEONTOLOGY OF ILLINOIS. 



rather irregularly arranged. Interspaces considerably less than 

 the diameter of the apertures in the central portion, but greater 

 towards the margins of the stipe. Zocecial tubes long, oblique 

 from their origin to the surface. Interzooecial space appearing 

 granular; under a higher power resolved into a very large num- 

 ber of exceedingly minute tubuli. Mesial lamina wavy in trans- 

 verse section, and scarcely distinguishable. 



This species is only provisionally placed with Euspilopora. It 

 presents some points of resemblance to the Silurian genus Phyl- 

 lodictya, but differs too strongly in other respects to admit of 

 its being referred there. It probably belongs to an undescribed 

 genus, but being unwilling to found a new genus upon unsuffi- 

 cient material, I prefer to arrange the species as above till more 

 of the numerous Hamilton species have ben thoroughly investi- 

 gated. 



I am indebted for the fine specimen figured to the Kev. W. H. 

 Barris, of Davenport, Iowa, in whose honor the specific name 

 is given. 



Position and locality: Hamilton group, Buffalo, Iowa. 



T^ENIODICTYA UMch. 



(For generic diagnosis see page 393.) 



TJENIODICTYA RAMULOSA Ulrich. 



LXVII, Fig. 1-lb. 



Zoarium a flexuous, dichotomously branching stipe, of con- 

 siderable height, 2 or 3 mm. in width and less than 1 mm. in 

 thickness, increasing in width before bifurcating, with essentially 

 parallel margins; attached by a small expanded base. Bifurca- 

 tions numerous, taking place at intervals of from 5 to 10mm. 

 Cell apertures arranged in longitudinal and curved diagonal 

 series, the longitudinal arrangement more pronounced in the center 

 and the curved arrangement towards the margins; about six in 

 2 mm. longitudinally; the oval apertures occupy the bottoms of 

 sloping areas; the latter are more or less confluent, sometimes 



