285 



Ilolotypo : 244-17. IiHli:iii;i T'liivcrsify. 



Genus Mcsotri/im I Irith. ({(Miotypo ; Diplotrypa iiifKla llricli. Itiplo 

 trypa (in part Niclidlson. ralodzoic Tabulate corals, 1S7!), p. .■;12 ; f^cnus 

 Monticulipora. ISSl. iip. 101. \r,~). Ulrit-h. Jour. Cincinnati Soc. Nat. Hist., 

 n. 18S2. p. 15:{. Fooni. Coiitr. Micro-Pal. Canil)ro-Sil., 1S83. p. 13. TTlrich 

 Geol. Surv. Illinois, 8, 1890, p. 378. 



Mesotrypa Ulrieli, Geol. Minnesota, 3. 1803, p. 2r)7. Xickles and P.assler, 

 Bull. IT. S. Geol. Surv., 173, p. 30. Bassler. Bull. V. S. (Jeol. Surv., 2!>2, IWK;, 

 p. 27. Gralmu and Shinier, N. A. Index Fossils, 1, 1007, p. 130. IlenniK, 

 Archiv. fur Zool.. 4. No. 21. 1008. ]>. 20. Bassler. I'.nll. V. S. Xat. Mus.. 77, 



1011, p. ion. 



Zoarium liemisi>lH'ric. conical, discoidal or iiicrustinj,'. It is j.;cnerally 

 free with an epitliica covering the Inise ; zooecia are polvfronal or circular 

 with curved, and sometimes funnel-shaped diaphragms, which are probably 

 modified cystiphragms ; zooecia more or less separated b.v angular meso- 

 pores. which become smaller with age, and are intersected by numerous 

 diaphragms ; acanthopores generally present. 



Mvxofrypa orustitlato n. sp. Plate V, Figs. 5-0. The zoariiun of this si>e- 

 cies forms incrustlng expansions about 2 mm. in thickness. In the type 

 specimen the zoarial mass consists in part of superimposed laj'ers and at- 

 tains a height of 8 to 10 mm. On the surface small low monicules of large 

 zoecia and numerous me.sopores are irregularly distributed, varying from 1 

 to 3 mm. apart. In places the surface rises into conical-like tubercles .5 to 

 1 mm. high, and from 8 to 12 mm. apart. 



The zoecia are thick-walled at the surface, circular, regularly arranged, 

 and in contact on 3 or 4 sides; 7i'2 to 8 intermonticnlar and "I'/o monticular 

 zooecia occur in 2 mm. 



The acanthopores are small, incon.spicuous, and unequally distributed. (» 

 to 7 about a zooecia in .some areas and in others no acanthoix>res are pres- 

 ent. 



Mesopora are abundant; more numerous at the base than in the mature 

 zone. Diaphragms are closely set ; 13 to 1~> in the distance of one mm. 



The diaphragms in the zooecia are in rather definite parallel transverse 

 horizons, separated by a distance equal to lyo to 2^2 tube diameters. Two 

 to six diaphragms 14 to y, tube-diameters apart are present in each zooecia 

 at the elevation of the common horizons. Curved and cystoid diaphragms 

 occur in the mature part of the zooecial tube only. 



The segregation of the small and inconspicuous acanthoiwres into areas 

 closely associated with the monticular zooecia, the zonal arrangement of the 

 diaphragm and the localization of the curved and cystoid diaphragms in the 

 peripheral portion of the zoarium are the conspicuous differentiating chai'- 

 acters of the species. 



Occurrence: Pierce limestone, Murfrccshoro. Teiiiicssee. 



Holotype: (92) U. S. Nat. Mus. 



Mesotrypa diibia. u. sp. Plate VI. Figs. 1-2. Zoarium consists of thin 

 expansions 2 mm. in thickness. Small inconspicuous maculae, consisting 



