GIRTY, yEW CARBOXIFEROUS FOSSILS 303 



in a thin lamellar expansion, a type of growth also possessed by another 

 species which can with propriety be placed here (LiocUma? araneum 

 Ulrich). It has rather numerous mesopores and rather rare and small 

 acanthopores. Diaphragms are fairly abundant in the zooecia, and they 

 are centrally perforated. The walls are thickened in the mature region. 

 All these characters belong also to Lioclema, from which the present type 

 is distinguished by the degree of their development. It differs from 

 Lioclema in the greatly reduced number of mesopores and the much 

 smaller acanthopores. The difference is so marked as to deserve separa- 

 tion into a distinct group, probably of subgeneric importance. 

 Type. — Pycnopora regularis. 



Pycnopora regularis sp. nov. 



Zoarium consisting of a thin expansion, one side of which is covered with a 

 wrinliled epitheca. Thicliness .5 to 1 mm. Zooecia circular, usually in con- 

 tact, the interspaces occupied by mesopores. generally 2 or 3 in a group. Eight 

 zooecia occur in 2 mm. The walls of the mesopores are of equal size with 

 those of the zooecia. and the mesopores are often not distinctly angular. Acan- 

 thopores are rare and small and imbedded in the rather thick walls so that 

 they do not indent the cells. The zooecia vary considerably in size, and there 

 are macuhe at rather wide intervals formed by groups of mesopores of various 

 sizes with which are usually associated a few large zooecia. The average 

 diameter of the apertures is .17 mm., but the larger ones measure .22 mm. 

 The tubes are prostrate foi- a short distance, later becoming erect and the 

 walls are somewhat obscurely moniliform. Tabuhp are fairly abundant, con- 

 sidering the length of the cells, and thev are in many cases incomplete when 

 seen in longitudinal section, owing to the central perforation. They seem to 

 be restricted to the zooecia. none having been observed in the mesopores. 



Pycnopora bella sp. nov. 



Zoarium in the form of a thin expansion. The zooecia are at first slender 

 and prostrate for a considerable distance, later erect. Near the surface, the 

 walls are somewhat thickened, and the apertiu-es are rounded. The apertures 

 occur about 8 in 2 mm. They have a diameter of .17 to .21 mm., the average 

 being nearer the smaller size. In spite of the rather thin walls, the zooecia 

 are usually but obscurely polygonal, owins to occasional mesopores and the 

 numerous acanthopores. ]\Iesopores are scantily developed and small, more 

 abundant on some areas than on others. Acanthopores are rather abundant 

 and rather large, more or less strongly indenting the cells. They are strik- 

 ingly tubulate. In addition to the acanthopores. the walls in some cases have 

 small granules along their margins. Diaphragms are rare and appear to be 

 restricted to the prostrate portion of the zooecia. 



This form resembles P. hirsnfa. from which it is distinguished by its 

 larger and less numerous acanthopores and thinnor walls. 



