BRYOZOA. 445 



STEXOPORA CARBON ARIA Worthen. 



PL LXXm, Fig. 8-8a. 



Ch(f fetes ? carlonaria Worthen. 1875. Geol. Sur. El.. VoL 6, p. 526. PL XXXII, Fig. 5. 

 Stenopora carbonaria Foerste, 1887. BulL ScL Lab. Denison Univ., VoL 2, p. 85. PL 

 VHI, Fig. 13a-c. 



Zoarium ramose, consisting of sub-cylindrical branches, vary- 

 ing in diameter from ten to fifteen mm. Surface smooth, not 

 exhibiting groups of cells marked by differing from the average 

 size. Zooecial apertures angular and sub-circular, with either 

 thick or thin interspaces, about ten or eleven in three mm. 

 Walls of zooecial tubes moniliform in the cortical region, the 

 swellings irregular, often merged into each other, at other times 

 separated by a thin interval; twelve to fourteen in two mm. 

 Thin centrally perforated diaphragms developed in the mature 

 zooecia and about a tube diameter apart; none were observed in 

 the axial region. Mesopores almost wanting. Acanthopores 

 large, fairly numerous. The divisional line between the thick- 

 ened portions of the walls of adjoining zooecia is marked by a 

 series of minute dark spots. 



The above describes the typical form of the species. Associated 

 with them are a number of other specimens offering certain 

 peculiarities that, while not very marked, are nevertheless suffi- 

 cient for identification. These I propose to designate as varie- 

 ties maculosa and confer! a. 



var. MACTLOSA Ulrich. 



PI. LXXTTT, Fig. 10-lOa. 



This differs from the typical form in having well-marked 

 groups of small cells, surrounded by zooecia apertures of larger 

 size than the average. Nine or ten of the ordinary size in three 

 mm. The diaphragms are also stronger and more numerous. 

 The branches too are generally somewhat stronger, being some- 

 times as much as twenty-five mm. in diameter. 



