Uhinldiotya.] BEYOZOA. 133 



manner causing the transverse interspaces to appear as bearing three longitudinal 

 striae or rows of granules. Margin of branches acute, the non-celluliferous band 

 rather wide and occupied by one or more lines of papillae. 



Of internal characters it will suflSce to mention that there is a well-developed 

 superior hemiseptum, and a greater number of median tubuli in the end spaces 

 between the zooecial apertures (see fig. 18) than in any other species known to me. 



This pretty little species is not likely to be confounded with any of the preced- 

 ing, unless it be with R. exigua. But the surface characters, especially when well 

 preserved, are so very dissimilar that confusion, even in that case, is inexcusable. 



Var. MODESTA n. var. 



PLATE V, FIG. 17. 



Under this subordinate name I propose provisionally to classify an associated 

 form, differing in some respects constantly from the typical variety. Both are rep- 

 resented by numerous specimens, with no question in any case as to where each 

 belongs. They agree, however, too closely in the more important elements of struc- 

 ture to admit of specific separation. Except in the case of subsequent discoveries in 

 other regions proving the supposed new variety to hold its own geographically, the 

 above degree of separation seems to me sufficient. My studies of the paleozoic bifo- 

 liate Bryo:^oa have taught me to distrust mere deviations in the width of the branches 

 as being good specific characters. 



In the variety the branches are wider, the width varying from 1.7 mm to 3.0 mm., 

 the zocEcial apertures larger, and the interspaces correspondingly narrower. Still, the 

 number of apertures in 5 mm., measuring lengthwise, is, as in the typical form, about 

 sixteen. In the best preserved specimens the superficial characters resemble those 

 of young examples of typical minima very closely, the chief difference_being that the 

 zooecial apertures, as already stated, are larger, and the non-poriferous band gener- 

 ally wider and grano-striated obliquely instead of longitudinally. The striae also 

 project slightly beyond the edge, causing the latter to be minutely serrate. 



When the drawings for this species were prepared I possessed, unfortunately, 

 only a few specimens. The number was subsequently greatly increased by pickings 

 from washings of shales from the original locality, kindly sent me by Mr. W. H. 

 Scofield, of Cannon Falls. 



Formation and tocaiif2/.— Galena shales, near Cannon Falls, Minnesota; associated with species of 

 Nematopora, Arthropora arniatum, Diastoporina flabellata, and other small Bryozoa characterizing the 

 horizon. 



Mus. Reg. No. 8105. Var. modesta, 8106. 



