22G SYSTEMATIC PALEONTOLOGY 



The measurements of the two specimens are: 



1 3 



mm. mm. 



Greater diameter of ealice 7 7.75 



Lesser diameter of ealice 6 5. .": 



Height of corallum 12.5 9.75 



The specimens on Avhich this species is founded are all imperfect. I 

 conld not obtain accurate details concerning the characters of the col- 

 umella or of the pali, but the species seems to present all the essential 

 characters of Troclwcyatlius and is therefore referred to that genus. 

 There is no other species of coral with which it could be confused; 

 therefore critical notes are unnecessary. 



Occurrence. — Aqitia Foemation. Potomac Creek, Aquia Creek, 1 

 mile northeast of Piscataway, Marlboro Point. 



Collections. — Johns Hopkins University, U. S. National Museum, 

 Maryland Geological Survey. 



Genus PARACYATHUS Milne-Edwards and Haime. 



Paeacyathus maeylandicus n. sp. 

 Plate LXI, Figs. 9, 9a, 9b. 



Description. — Corallum Ioav, subcylindrical, attached by a wide and 

 somewhat expanded base. Dimensions: greater diameter of ealice, 5.75 

 mm.; lesser diameter of ealice, 5 mm.; height of corallum, 5 mm.; great- 

 est width of base, 6.5 mm. 



Outer surface of corallum glossy, apparently epitheca is present. Cos- 

 tae corresponding to all septa, low, alternately larger and smaller in 

 size near the calicnlar margin, but equal near the base, densely granu- 

 lated and slightly crested along the summit. Granulations also present 

 between the costae. Upper septal margins very slightly exsert. Septa 

 crowded, thin, in four comjDlete cycles; the six primaries slightly the 

 largest and somewhat more prominent; the secondaries slightly smaller 

 than the primaries; the quaternaries are the smallest and the least prom- 

 inent. The septal faces, beset with small, low, conical granules. Septal 

 margins entire, sometimes transversely undulate. Pali present before 

 all except the last cycle of septa and arranged with diagrammatic regu- 



