﻿ULRICH-BASSLEU] REVISION OF PALEOZOIC BRYOZOA 3 5 



having no mesopores and so many small acanthopores indenting the 

 zooecial walls thai the surface appears granulose rather than spin 

 which term applies better in other species of the genus. Continuing 

 the comparison with .V. crenidata, the zocecia are found to be a little 



smaller, about i<> occurring in 2.0 mm., and the axial portion of the 

 tube walls straighter. 



Thin sections of this species are both beautiful and instructive. In 

 vertical sections the periodic development of the acanthopores, which 

 is a feature of the genus, is shown especially well. Diaphragms few 

 and of irregular distribution. 



Occurrence. — Richmond formation. Versailles. Indiana. 



Cat. No. 43,200, U. S. X. M. 



STIGMATELLA PERSONATA new species 

 (Plate XII. 1 3) 



This is one of the non-mesopored species of the genus and forms 

 smooth, branching zoaria very much like .V. crenidata and S\ spinosa. 

 From the former it is distinguished by having fewer acanthopores, 

 no mesopores, and in lacking the crenulation of the walls in the 

 immature region. From S. spinosa it is separated by its larger 

 zocecia, 7 to 8 being found in 2 mm. while 10 are required in that 

 species to cover an equal distance. The acanthopores in S. personata 

 also afford a difference, being but seldom more numerous than the 

 junction angles which they usually occupy. In 5. spinosa, it will be 

 remembered, they are so abundant that they almost completely sur- 

 round the zocecium. 



Occurrence. — Uncommon in the Richmond formation at Hanover, 



Ohio. 



Cat. No. 43.201, U. S. N. M. 



STIGMATELLA INTERPOROSA new species 

 (Plate XII. 4- 5) 



Associated with S. crenidata but distinguished by smaller, more 

 irregular growth, the branches frequently intertwining and being oi 

 all shapes from small cylindrical, 3 or 4 mm. in diameter to irregular 

 fronds 10 mm. or more broad. About 9 zocecia in 2 mm. 



Mesopores with diaphragms their own diameter apart: zocecial 

 tubes with few diaphragms. Zocecia usually separated by numerous 

 mesopores. Acanthopores small and relatively few in number. 



The small zoarium. smooth surface, small and few acanthopores 

 and numerous mesopores are the specific characters. 



