582 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



formation at Oregonia, Waynesville, Clarksville, Hanover, and other 

 localities in Ohio and at several localities in southeastern Indiana. 

 Cat. Nos. 40234-1:0236 Harris collection, 41755, 41756. U.S.N.M. 



HOMOTRYPA RICHMONDENSIS, new species, 

 riate XXIV, figs. 1-4. 



The more or less prominent tubercles, few mcsopores, numerous 

 acanthopores, and aljsence of diaphragms are characteristic of this ; 

 species. The zoarium consists of ramose, somewhat flattened l)ranches, ; 

 varying from smooth to slightly tuberculated. Zooecia thin-walled,:, 

 cio-ht in 2 mm. Acanthopores numerous, small. Mesopores few, as 

 a rule restricted to the clusters. Diaphragms wanting; cystiphragms ^ 

 well developed. 



Although resembling several species in one or more details, the 

 combination of characters readily distinguishes this form. For exam-i 

 pie, specimens of JI. wortheni, with the tubercles poorly developed, 

 are very similar externally, but internally are distinguished by the 

 presence of diaphragms. 



Occurrence. — Not uncommon in the lower and middle divisions of 

 the Richmond formation at Eichmond and Versailles, Ind.; and at 

 Hanover, Oxford, and other localities in Ohio. 



Cat. Nos. 41784-41787. U.S.N.M. 



HOMOTRYPA NODULOSA, new species. 

 Plate XXIII, figs. 5-11; Plate XXV, fig. 15. 



Zoarium ramose, growing from an expanded base attached to othe]i 

 organisms; branches cylindrical or slightly compressed, 2.5 to 6 mm 

 in diameter. Surface with small, well-marked, sharp tubercles, ano 

 bristling with large acanthopores. Apertures irregularly polygonal, 

 direct, thin-walled, about nine in 2 mm. At the surface there are tw(, 

 sets of acanthopores, one set very large, perforated, and distributecj 

 at rather regular intervals, the other much .smaller and more numer 

 ous. Tangential sections seldom show the smaller set because of thei , 

 shortness. Mesopores numerous, though less so when the acanthaj 

 pores are greatly developed. Walls thin in the axial region am 

 considerably thickened in the peripheral. Cystiphragms sparing!; 

 developed and restricted to the early portion of the mature regioDil 

 Diaphragms wanting in the zooecial tubes, but abundant and muc 

 thickened in the mesopores. Vertical sections show that the larg 

 acanthopores may arise in the axial region and proceed at variou 

 angles to the surface, and are crossed by thin, transverse partitiou^ 

 The structures supposed to be communication pores are often seen i 

 tangential sections. 



