Description of a J^ew Genus and some New Species. 121 



ranged. A. ortoni grows in small, subcircular expansions, is almost 

 invariably attached to the valves of Stroiohomena alternata, and does 

 not to m}^ knowledge occur in strata below three hundred feet above 

 low water mark at Cincinnati; while A. hirsuta sometimes covers an 

 Eadoceras for the space of five inches or more, and has not been found 

 above the two hundred feet line of strata. Other distinctions might 

 be pointed out, but those mentioned are sufficient for the identification 

 of the species. 



Formation and localit3': occurs rather rarely a few miles south of 

 Covington, Ky., at an elevation corresponding to that of one hundred 

 and fifty feet above low water mark in the Ohio river at Cincinnati, O. 



Collectors: H. E. Diokhaut, E. O.Ulrieh. 



Atacxopora MA.CULATA, u. sp. (Plate XII., figs. 2, 2a, 2&, 2c.) 



{'Ei-y —Ma oulatus, spotted.] 



Bryozoary parasitic, growing into expanded crusts, which vary in 

 thickness from less than one quarter of a line to two lines; the usual 

 thickness is about one half a line. All the specimens observed are 

 attached to species of Orthoceras or Endoceras. Surface exhibiting 

 rounded or elongated tuberosities, which are abruptly elevated, and 

 from one fourth to one half a line in diameter, sometimes they are ar- 

 ranged in quite regular diagonal lines, but usually are irregularl}' dis- 

 tributed over the surface; measuring from their centers, the distance 

 that they are apart varies from one to nearlj' two lines ; summits of macu- 

 lae somewhat flattened and compact. Tube orifices sub-equal, moderate- 

 ly thin-walied, polygonal, about eight in the space of one line; intersti- 

 tial tubuli few or entirely absent. Pseudo-septa well developed, though 

 not often observable at the surface. Superior edges of tube walls, 

 when well preserved, carrying a few small spines. 



Transverse sections show the pseudo-septa very distinctly projecting 

 into the tube area. They number from one to four or five, and are verj- 

 irregularly distributed. In sections of this kind the maculae present 

 the appearance of clusters of minute tubuli, which undoubtedly is their 

 true nature. In longitudinal section the tubes are usuall}- without 

 tabulae, though these structures are not infrequently developed in 

 moderate numbers. The maculae appear minutely tubular, and are 

 divided into distinct floors, that run parallel with the outline of the 

 projection of the tuberosities on the surface. In a specimen one line 

 in thickness, there are about five of these floors. 



This is a common species, and, by collectors is frequently confounded 



