SPECHTS FERRY BRYOZOAN FAUNA 



27 



most commonly two to five, zooecial diameters apart but in mature zone generally 

 spaced one-half zooecial diameter or less apart. Diaphragms in mature zone 

 commonly arched, convex outward, and uniting with adjacent proximal diaphragm. 

 Zooecial walls thin, straight or mildly flexuous in axis and perceptibly thickening 

 near base of mature zone. Zooecial walls in mature region generally integrate, 

 consisting of acute A-shaped laminae and containing a centrally located mildly 

 undulatory black divisional line passing through the apices of the laminae; less 

 commonly, walls obscurely integrate or amalgamate and composed of laminae more 

 broadly convex outward. Zooecial wall material continuous into diaphragms, par- 

 ticularly in zooecia having distinctly integrate walls. Closely tabulate tubes, be- 

 low average in size and confined to mature zone, rare and interpreted as mesopores, 



Remarks. — This species is represented in the Spechts Ferry collections by 

 twenty-two sectioned specimens. 



Batostoma winchelli shows considerable variation in structure, particularly 

 in tangential sections. Acanthopores vary in abundance not only from specimen to 

 specimen but, in a more striking manner, within the same zoarium. In some speci- 

 mens, however, acanthopores are uniformly abundant throughout the section. In 

 other specimens acanthopores are abundant (three to five with each zooecium) in 

 part of the section but are comparatively rare (one to three associated with ten 

 zooecia) elsewhere in the section. Further, acanthopores vary considerably in 

 prominence; a few of the Spechts Ferry specimens have acanthopores comparable 

 in size to those figured by Ulrich (1895, pi. 27, figs. 4, 6) but in most specimens 



-no 



110- 



-100 ^^ 



100- 



-90 slff' 



90- 



- 80 



80- 



- 70 £ 



"60 | 



* 1 



- 50 







| 70- 

 <b 



| 60- 



50- 



- 40 ^1 







40- 



-30 ;:;';: ' 





30- 



- 20 





20- 



- 10 







In 10- 



6-6+ 8-8+ 



.16 .14 .12 .10 .08 .06 .04 .02 



7-7+ 9-9+ 



.15 .13 .11 .09 .07 .05 .03 



ZOOECIA IN 2 MM 



ZOOECIAL WALL THICKNESS, MM 



Text fig. 3 - Measurements on Batostoma winchelli (Ulrich) 

 6+ signifies six entire zooecia and part of 

 seventh in a 2-mm distance. 



