166 BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



and superior hemisepta in the same region of the zooecia. Views of a 

 tangential section under several magnifications are given in figures 

 83 h and c, while in figure 83 d the structure of a macular area with 

 its neighboring zooecia is shown. The latter section was prepared 

 from an old example in which the small pores or granules are well 

 developed. Here also the mesopores forming the macular area have 

 been partially closed by a dense tissue. 



Externally Nematotrypa gracilis can readily be distinguished from 

 other Ordovician bryozoans by its slender branches of small, oval 

 zocEcia, isolated by exceedingly minute and numerous thin-walled 

 angular mesopores. The internal features are too different to require 

 comment. 



Occurrence. — A common fossil of the Kuckers shale (C2), Baron 

 Toll's estate, Esthonia, where the types were found. Other forma- 

 tions and localities are the Jewe limestone (Dl), Baron Toll's estate, 

 the Echinospherites limestone (Cl), 4 miles east of Keval, an:d the 

 Chasmops li estone, near Bodahamn, on the island of Oeland. 



Coty pes. —Cat. Nos. 57258, U.S.N.M. 



Specimens and thin sections from the Kuckers shale, Baron Toll's 

 estate, and from th Chasmops limestone, island of Oeland, are in 

 the British Museum. 



FamHy EHINOPORIDiE Ulrich. 



A single genus and species of this rather unique family is present 

 in the Russian faunas under study. In a former publication ^ I have 

 pointed out the following characters for the family, which may in 

 some respects be considered one of the simplest divisions of the 

 Cryptostomata. 



Zoarium variable in form; zooecia prone along the basal membrane, simple, oblong, 

 or rbomboidal; vestibules direct, hemisepta wanting or almost so; front of zooecia 

 below vestibule commonly strengthened with solid or vesicular tissue. 



Genus LICHENALIA Hall. 



Lichenalia Hall, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 401; Nat. Hist. New 

 York, Pal., vol. 2, 1852, p. 171.— Bassler, Bull. 173, U. S. Geol. Surv., 1900, 

 pp. 54, 299; Bull. 292, U. S. Geol. Surv., 1906, p. 60. 



In the search for bryozoans in the solid limestones of the Borkholm 

 formation numerous thin, epithecated, subcircular expansions were 

 encountered in a more or less fragmentary state while breaking the 

 rock. These at once recalled the very similar expansions occurring 

 in the Niagaran (Rochester) shales of western New York and desig- 

 nated by Hall as Liclienalia concentrica. Upon the preparation of 

 numerous thin sections and a study of microscopic characters this 

 surmise was found to be correct, for no differences of any specific 



1 The Bryozoan Fauna of the Rochester Shales, Bull. 292, U. S. Geol. Surv., 1906, p. 59. 



