208 SYSTEMATIC PALEOXTOLOGY 



laterally compressed c-nrYed brandies, 2 to 3 mm. wide or liigli and 

 1 mm. or less thick, throwing of: similar branches from their sides. Oc- 

 casionally they appear to divide dichotomonsly, bnt this probably is not 

 really the case. The zooecial apertures are subcircnlar or oval, 0.08 to 

 0.10 mm. in diameter, arranged in more or less irregular transverse 

 series, five or six in 1 mm., oblique, with the peristome higher behind 

 than in front. Except for an occasional large cell (? zooecium) the 

 lower third or half of the branches is without zooecial apertures and in 

 the worn condition may appear quite solid. When in a good state of 

 preservation, however, this part of the surface is covered by angular 

 depressions, of varying sizes, the centers of the depressions usually show- 

 ing the mouth of a small pore. Similar pores extend upward and oc- 

 cupy the depressed spaces between the rows of zooecial apertures. Gon- 

 ocysts of the same type as in Berenicea, Discosparsa and Fascipora. 

 The zooecial tubes pass through them without interruption, but the 

 mesopores do not. Closures of zooecial tubes, some distance below the 

 external orifice, appear to have a central perforation. 



A species recently described by Pergens (loc. cit) from the Cretaceous 

 (Senonien) of France, under the name of Bicrisina gaudryana, is either 

 the same as R. dicliotoma or extremely like it. The species occurs in 

 the Upper Cretaceous at Timber Creek and Vincentown, IST. J. 



Occurrence. Aquia Foemation. Upper Marlboro. 



Collection. — Maryland G-eological Survey. 



Family CERIOPORIDAE. 



Genus CAVARIA Hagenow. 



Cavaeia dumosa n. sp. 

 Plate LIX, Figs. 4-8. 

 Description. — Zoarium forming small, bushy masses, consisting of fre- 

 quently and irregularly dividing and coalescing branches, varying in 

 thickness generally from 1.5 to 2.0 mm., but occasionally reaching 3.0 

 mm. Surface of the most nearly perfect specimens exhibiting at irreg- 

 ular intervals; small, slightly depressed maculae, smooth or occupied 

 solely by mesopores. In these speeimeus the zooecia are readily dis- 

 tinguished from the mesopores by their prominent peristomes and 



