PLATE XLII. 



PAGE 

 Fig. 1. DlCHOTBYPA GKWfDIS Ulr 498 



1, Portion of the type specimen, natural size. 

 1 a. Surface of same x9. 



1 6. Portion of vertical section x!8. 



1 c imd 1 d and 1 e. Three parts of a tangential section, x!8, showing the struc- 

 ture at different levels. 

 Niagara group. Kankakee Co., 111. 

 Illinois State Museum. 



Fig. 2. DICHOTBYP A FOLIATA Ulr 499 



2 and 2 a. Two fragments, natural size. 



2 b. Surface x9, presenting the usual appearance. 



2 c. Tangential section x 18, cutting the zooecia just beneath their apertures. 

 2 d. Tangential section, x!8, showing structure near the median laminae. 

 2 e. Transverse section x!8. 



2 / and 2 g. Two vertical sections x!8; the first shows well developed super- 



ior hemiseptum. 



Hamilton group. Buffalo, Iowa. 



E. O. Ulrich's collection. 



Fig. 3. TJENIOPOBA OCCIDENTALIS Ulr 505 



3. Fragment of this species, natural size. 



3 a. Surface of same x9, showing linear arrangement of zooecia. 



3 b. Tangential section x!8, showing one of the four faces, and. near the left 



margin, the sharply defined vertical lamina. 

 3 c. Transverse section x!8, showing thickness of outer portion of zoarium. 



Hamilton group, Buffalo, Iow,a. 



E. O. Ulrich's collection. 



Fig. 3 d. T.SNIOPOBA PENNiFOBsns Nicholson 505 



Transverse section of this species introduced for comparison with flg. 3c. 

 Hamilton group, Eighteen Mile Creek, N. Y. 



Fig. 4. CYSTODICTYA HAMEC/TONENSIS Ulr , ...493 



A group of stems showing mode of branching, natural size, 

 Hamilton group, Buffalo. Iowa. 

 E. O. Ulrich's collection. 



