[to.i323. STRUCTURAL FEATURES OF HOMOTRYPA—BASSLER. 585 



region is reached. As a rule, both cystiphragms and diaphragms are 

 iibsent in the peripheral region of the ordinary zooecia, but in those of 

 :he maculjB there is an abundance of the former. 



I This species is named after its discoverer, Dr. George M. Austin, 

 bf Wilmington, Ohio, who, notwithstanding arduous professional 

 duties, finds time for enthusiastically collecting and studying the 

 fossils of that region. 



Occurrence. — Abundant in the middle division of the Richmond for- 

 mation at Dutch Creek, 41 miles northwest of Wilmington, Ohio, and 

 at Cowans Creek, 7 miles southwest of the same place. 



Cat. No. 41762, U.S. N.M. 



HOMOTRYPA CYLINDRICA, new species. 

 Plate XXII, tigs. 8-13. 



Zoarimn ramose, branches long, cylindrical, from \ to 15 mm. in 

 diameter, dividing dichotomousl}' at intervals of from 3 to -1 cm. 

 Surface varying from smooth to tuberculated, the macule or monti- 

 cules generally somewhat transversely elongated. Zooecial apertures 

 thick walled, usually angular, direct, about nine in 2 mm. Mesopores 

 few, seldom occurring outside of the clusters. Only well-preserved 

 examples show at the surface the numerous and very large acantho- 

 pores characteristic of the species. The walls of the zooecia in the 

 axial region are thin and but little crenulated, but in the mature 

 region they become so thickened as to almost equal in breadth the 

 diameter of the zooecial cavity. Cystiphragms well developed. Dia- 

 phragms very few, if present at all, the structures simulating them 

 probably being large cystiphragms. 



The large and nimierous acanthopores and the thickness and minute 

 structure of the walls give a very characteristic, even bizarre, appear- 

 ance to tangential sections. The number of acanthopores varies, the 

 normal number being four to five when the}^ are large to five to nine 

 smaller ones around a zooecium. In vertical sections the acanthopores 

 are seen not only to proceed directly to the surface parallel with the 

 zooecial walls, but they also sometimes cross them obliquely. 



Occurrence.— ^\^\\mo\\^\ formation, Richmond and Versailles, Indi- 

 ana, and Oxford, Ohio. 



Cat. Nos. 41757-41759, U.S.N.M. 



HOMOTRYPA RAMULOSA, new species. 



Plate XXV, figs. 1-4. 



Zoarium consisting of subcylindrical or somewhat compressed stems 

 from which branches proceed frequently and without regularity; an 

 average example is 8 cm. high and 8 to 12 mm. in thickness. Surface 



