296 



BULLETIlsr 11, UNITED STATES NATIONAL MUSEUM. 



istic. In vertical sections the walls in the immature zone are seen 

 to be thin and crenulated. An occasional incomplete diaphragm 

 occurs here as well as in the mature zone, although they are scarce 

 in the latter region. The mesopores when not obscured by the dense 

 tissue of the interzooecial spaces are distinctly beaded and have dia- 

 phragms about their own diameter apart. 



Externally the narrow, cyUndrical branches, polygonal thick- 



FiG. 181.— Hemipheagma macxjlattjm. a, a feagment, x2, ExmBiTmG portions of two macule;; 



6, TANGENTIAL SECTION, X20, THROtTGH THE INTEEMACULAR ZOCECIA; C, SEVERAL ZOCECIA OF THE SAME 

 SECTION, X40; d, VERTICAL SECTION, X20, THROUGH THE ENTIRE WIDTH OF A BRANCH. KUCKEES SHALE 



(C2), Reval, Esthonia. 



walled zooecia with numerous very minute angular mesopores, will 

 readily serve for the identification of H. maculatum. The incom- 

 plete diaphragm, crenulated walls, and small mesopores are especially 

 characteristic of tliin sections. 



Occurrence. — Not uncommon in the Kuckers shale (C2) at Reval, 

 and Baron Toll's estate, Esthonia. 



Eolotype.— Cat. No. 57428, U.S.N.M. 



British Museum, thin section of the type-specimen. 



HEMIPHRAGMA BATHERI, new species. 

 Text fig. 182. 



The zoarium of this well-marked species is of small, frequently 

 branching, cyhndrical stems averaging 2 mm. in diameter. The sur- 

 face is smooth and presents no conspicuous maculae, as in the preced- 

 ing species, although clusters of larger zooecia and more numerous 

 mesopores are present as usual. Zooecia polygonal, thick-walled, with 

 solid interzocEcial spaces; fi,ve to six zooecia in 2 mm. Acanthopores 

 small, sometimes numerous at the surface where they occur along the 

 crest of the zocecial wall. Mesopores few, averaging about one to a 

 zooecium, usually filled by the dense tissue forming the solid interzooe- 

 cial spaces. Through this tissue the outlines of the mesopores are 

 visible in thin sections. 



