284 



Zoarium consists of parasitic and laminate expansion which in some spe- 

 cies rises into domed or gloltular masses. The wall strnctnre reseml)les the 

 Heterotrypidae more than the Monticuliporidae. The acanthoixjres are well 

 developed and sharply defined. The cystiphragms, which appear as curved 

 diaphragms, form the ha sis for the assignment of the genus to the family 

 Monticuliporidae. 



Orhignella nodosa, n. sp. Plate V. Figs. 1-2. The zoarium forms small 

 and large incrusting expansions, that rise into nodular masses of irregular 

 forms and sizes, by superposition of layers ; nodules are luiequally distrib- 

 uted. Slabs have been collected on which there are numerous colonies that 

 are contiguous and overlap one another, forming an incrustal covering 

 of many square inches. The nodules vary in height from .5 mm. to 10 mm., 

 with a corresponding variation in width. 



The surface is even ; twenty-four maculae of large zooecia occur in one 

 sq. cm. 



The zooecia are polygonal, and have relatively thick wall ; 8 to 9 occur 

 in 2 mm. Mesopores are absent. Acanthopores are about as numerous as 

 the zooecia. located at the tube angles, and of large size, causing slight 

 inflection of the zooecial walls in most cases. 



The zooecial tubes of each laminar expansion are about .7 mm. long, with 

 3 to 4 horizontal or from 1 to ?> cystoid diaphragms in the space of one tube 

 diameter. 



The nodular zoarium. lack of monticules, and more numerous cystoid dia- 

 phragms distinguish the species from Ohignyella loeatherhyi. Orhignyella 

 lamellosa has large zooecia. less curved diaphragms, and much longer 

 zooecial tubes than O. nodosa. The large acanthopores and zoarial forms 

 of 0. nodosa are distinct differences which separate it from O. suilamellosa. 



Occurrence : Lebanon limestone. Rig Sitrings. Rutherford Tounty, Ten- 

 nessee. 



Holotype, 248-lG. Indiana T^niversity. 



Orhif/nyella multitahiiJata. n. sp. Plate V, Figs. 8-4. Zoarium. lamni- 

 nted, depressed, conical domes, rising from a wide base. The lower surface 

 of the mass is covered with a wrinkled epitheca. The type specimen is 9.5 

 cm. in diameter and 2.5 cm. high. The surface is smooth, with inconspicu- 

 ous clusters of large zoecia. 



Mesopores are very few. occurring in the maculae only. The zoecia are 

 angular, thin-walled ; 8 to 8^/^ in 2 mm. Large well developed acanthopores 

 with distinct lumen are present at most every tube angle. 



The zooecial tubes of a single lamina are 1 to .3 mm. long, crossed by 4 

 to 5 horizontal diaphragms in the space of one tube diameter. Cystoid, 

 curved or infundibular diaphragms occur in every tube. 



The crowded horizontal diaphragms, thickness of laminae, large acan- 

 thopores, and manner of zooecial growth, are a combination of characters 

 not found in any other species of the genus yet described. 



Occurrence: Pierce limestone; in sink hole at Almaviile, Rutherford 

 County, Tennessee. 



