326 THE PALEONTOLOGY OF MINNESOTA. 



LAuolotichUi. 



outer side in which very fine transverse lines may be noticed. Dimensions of 

 zooecium of average size, about 0.3 by 0.4 mm. Interstitial cells varying greatly in 

 size and distribution, some being very small, others as large and even larger than 

 the zocecia. They form generally but a single series between the zooecia, yet it 

 is not uncommon to notice a double row for a short distance. An obscure radial 

 arrangement, with the zooecia in contact lengthwise, is noticeable about certain 

 points, 6 mm. or more apart, where the interstitial cells are more numerous than 

 elsewhere, without, however, at any time being in sufficient numbers to justify 

 being called "maculae." 



Vertical sections are even more characteristic, since in these the loose construc- 

 tion mentioned is very striking. The zooacia appear as long irregular tubes crossed 

 at variable intervals by exceedingly delicate horizontal diaphragms. The average 

 distance between the diaphragms depends somewhat upon the horizon from which 

 the specimen was collected. In zoaria from the lower and middle thirds of the 

 Trenton shales, the average is between 0.5 and 0.9 mm., but in those from the Galena 

 shales it is between 0.8 and 1.2 mm. The interstitial cells assume all sorts of shapes, 

 but are always extremely high. A tendency to arrange themselves in vertical series 

 is usually manifest, but they cannot be said to form tabulated tubes, their walls 

 being on the whole quite irregular and the end partitions more or less oblique and 

 in many cases overlapping. All the walls have that peculiar granular structure 

 noticed, in paleozoic Bryozoa, only among the Ceramoporidce, and Flstuliporidce. 



Both the external and internal characters of this species are so distinctive that 

 there is little or no danger of confusing it with associate massive forms. 



Formation and locality. Not rare in the three divisions of the Trenton shales at Minneapolis, St. 

 Paul and Cannon Falls. It reappears, larger than ever, in the upper part of the Galena shales at several 

 localities in Goodhue county, Minnesota, and at Decorah, Iowa. The original Manitoba type of the 

 species I now believe to have come from strata equivalent to the last. It was collected at St. Andrews. 



Mus. Reg. Nos. 5963, 7602. 



Genus ANOLOTICHIA, Ulrich. 



Anolotichia, Ulrich, 1890. Geol. Sur. 111., vol. viii, pp. 381 and 473. 



Zoaria large, irregularly ramose or digitate. Zooecia comparatively large, form- 

 ing long prismatic tubes, intersected by complete diaphragms more or less remotely 

 situated. Walls thin, appearing transversely lineate in vertical sections. Apertures 

 angular or subovate, direct, with a distinctly elevated lunarium. Thin sections show 

 the lunarium to be traversed lengthwise by from two to seven minute, closely tabu- 

 lated tubes. Mesopores very few in A. impolita, but moderately abundant, rather 

 equally distributed among the zocecia, and of irregular form, in the type species. 





