MARYLAND GEOLOGICAL SURVEY 423 



pearance of the celluliferous surface varies greatly in different speci- 

 mens, the difference being due chiefly to the presence or absence and 

 number of the avicularia and ovicells. The latter appear as bulbous 

 inflations with a slit running from the center to one edge. When they 

 occur at all it is usually in abundance. Of avicularia there are at 

 least two sets, the larger ones occurring on the front of the zooecia, 

 forming its highest part and causing it to appear inflated. Those of 

 the smaller set occur in the depressed spaces, usually close beside the 

 zocecial orifice, and rarely on the reverse of the branches. 



This common species of tlie Choptank formation apparently belongs 

 to the Rctepora-cellidosa group of "Waters. Though resembling sev- 

 eral of the species of the group rather closely we could not decide 

 that it was any nearer to one than to another. Still, having found it 

 difficult to make thoroughly satisfactory comparisons, we will not be 

 greatly surprised should future study prove R. doverensis to belong to 

 some previously described species. 



Occurrence. — Choptank Formation. Dover Bridge, Jones Wharf. 



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



Family LEPRALllD/E. 



Genus LEPRALIA Johnston. 



Lepralia maculata n. sp. 

 Plate CXV, Figs. 8, 9; Plate CXVIII, Fig. 7. 

 Description. — Zoarium beginning as a thin sheet on shells of small 

 gastropoda to which other layers are added until masses as much as 

 two inches in diameter result. Surface of masses generally exhibit- 

 ing more or less distinct, usually elevated, clusters of zooecia slightly 

 larger than those occupying the intermediate spaces. Zooecia con- 

 vex, subovate, not sharply separated nor exhibiting any obvious plan 

 of arrangement; when in rows about six occur in 2.0 mm. Orifice 

 not terminal but situated in the anterior half, rounded and expanded 

 above, contracted below the middle where there is a small denticle on 

 each side, and nearly straight or curved slightly outward on the lower 

 side: peristome simple, not elevated. Surface punctate, excepting 

 over a space just beneath the orifice that is smooth and elevated into a 



