124 Cincinnati Society of Natural History. 



diameter; all the specimens examined are attached to fronds of 

 Ghcetetes {3Ioniiculipora) mammulatus ; tliickness of colony not ex- 

 ceeding one sixth or one fourth of a line. Distributed over the sur- 

 face at distances apart of one or one and a half lines, are low and 

 rather broad monticules, which carry groups of slightly larger sized 

 tube calices than the average, and occasionally a few minute tubuli. 

 Monticules variable in size and height, while their arrangement can 

 scarcely be called regular, though an approach is made toward such a 

 feature. Tubes thin-walled, sub-equal, somewhat oblique to the sur- 

 face near the margin of the expansion, but becoming more direct as 

 the middle of same is approached. Tube calices oval to sub-rhom- 

 boidal, about eight in the space of one line, their margins thin, and 

 carrying at the angles of the tubes small spines, which, when worn, 

 prove to have been hollow; these hollow spines probabh^ are of the 

 same nature as the intertubular cells in many bryozoa. Pseudo-septa 

 quite prominent, varying in number from three to five in each tube. 



A. tenella is closely allied to both A. ortoni and A. mundula. From 

 the former it is distinguished by the compact character of the monti- 

 cules, the presence of granulated tube walls, and absence of intertubu- 

 lar cells in that species. From A. mundula it is separated by the 

 laro-er size of the tubes, less prominent tubercles, thinner tube walls, 

 and smaller number of interstitial cells in A. tenella. 



Formation and locality: found near tops of hills about Cincinnati, O. 



Collector: E. O. Ulrich. 



Atactopora sdbramosa, n. sp. (Plate XIL, figs. 6, 6a, 66, 6c.) 



[Ety. — Subratnosiis, somewhat branching.] 



This is not a'truly parasitic species, though attached by a broadly 

 expanded base to foreign objects. In certain portions of the bryo- 

 zoary there appears to have been an excessive growth, the consequence 

 of which was the development of large nodes, or of short and thick 

 branches. Diameter of branches about four lines. Surface without 

 monticules. Tubes small, polygonal, quite irregular in size and ar- 

 rangement, and with numerous minute intertubular cells; the latter 

 are at irregular intervals collected into groups; of the interstitial tubuli 

 the groups alone arc distinguishable on the surface, those interspersed 

 between the ordinary tubes being apparently closed, and can only be 

 detected in thin sections. Tube calices of irregular shape, usually 

 nearly closed by accretions to the margins; in the open calices the 

 margins are thick and smooth; pseudo-septa not invariably developed, 



