274 Systematic Paleontology 



so numerous as to isolate the zorecia. Acanthopores inimerous, small, 

 noticeable only on exceptionally well-preserved surfaces. 



In tangential sections showing the fully matured condition, each 

 zooecium has from 2 to 4, commonly 3, of the small acanthopores in its 

 walls. The latter are of medium thickness for the genus, and about twice 

 as thick as walls separating adjoining mesopores. The zocecial tubes in 

 vertical sections are seen to be without diaphragms in the axial region 

 and to have, according to the size of the specimen sectioned, from 1 to 3 

 in the peripheral. The mesopores, on the contrary, have numerous dia- 

 phragms, these being distant from each other their own diameter or less. 



This species is closely related to L. wilmingtonensts Ulrich on the one 

 hand, and L. occidens (Hall and Whitfield) on the other, differing from 

 the first, which is from the Eichmond of Illinois, in having the diaphragms 

 less crowded in the mesopores, and from the latter, a common species in 

 the Upper Devonian of Iowa and Missouri, in having these structures 

 more numerous. L. suhrainosum differs from both the species mentioned 

 in having much fewer mesopores, while its acanthopores are both more 

 numerous and stronger. 



Occurrence. — Heldekberg Formation, Keyser Member. Keyser, 

 West Virginia ; Cash Valley, Maryland. 



Collections. — Maryland Geological Survey, U. S. National Museum. 



Lioclema pulchellum n. sp. 

 Plate XLIII, Figs. 9-12 



Description. — Zoarium incrusting foreign objects and varying from .5 

 to 1.0 mm. in thickness ; surface even, the clusters of large cells or meso- 

 pores being scarcely discernible. Zooecia subcircular to slightly petaloid, 

 5 to 6 in the space of 2 mm., separated from each other by from one to 

 three rows of rather small, angular mesopores, the latter open at the sur- 

 face. Acanthopores small, as usual increasing in size with age ; in the 

 matured region, 2 to 4 surround a zocccium and slightly indent its walls 

 so as to give the petaloid appearance. Vertical sections show that wJiile 

 the zocecial tubes are without diaphragms, the mesopores are rather closely 

 tabulated, the partitions being usually about two-thirds of their diameter 



