84 THE PALEONTOLOGY OF MINNESOTA. 
(Lichenaria. 
a species probably without septa, but the corallites are described as “slender cylin- 
drical tubes which may be in contact or separate”, and “the aspect of the species is 
remarkably like that of Syringopora.”  — 
Small colonies of Lichenaria typa look much like a mass of Conchicolites flexuosus 
Hall, as figured by Prof. Hall (Pal. New York, vol. vii, pl. cxv, fig. 19). The apertures 
of the latter are also polygonal in outline, but beyond this the two species are 
totally unlike. 
A very small colony of this species, figured on plate G, fig. 11, has given off a 
single corallite in a manner which is characteristic of Aulopora? trentonensis, n. sp. 
This corallite has developed three other buds, which have elevated the calyx of the 
parent, as in Aulopora. Where there are no young corallites infringing upon it, the , 
wall is circular in outline, with three distinct angles along the side from which the 
buds have originated. The polygonal outline of the cells of compound corals is prob- 
ably due to lateral crowding of the corallites. In nearly every case observed by us, 
when the cells are round in outline, they stand out free from the colony.* 
Formation and locality.—Not rare in the Trenton shales near Minneapolis, Minnesota. Mr. Ulrich 
writes us that he has specimens which ‘undoubtedly belong to this genus and probably are specifically 
the same as typa, from the Black River limestone at Pauquette Rapids, Canada.” 
Collectors.—E. O. Ulrich and C. Schuchert. 
LicHENARIA MINOR, 2. sp. (Ulrich.) 
Fig. 5. 
Fig. 5. Lichenaria minor Ulrich, Trenton shales, near Cannon Falls, Minnesota. a, an example of 
this species, growing as usual upon a ramose bryozoan ; b, small portion of same with the corallites 
opening more direct than usual, x3. 
Corallum attached parasitically to foreign bodies (chiefly ramose bryozoa) over 
which it forms irregular patches 1 mm. or a little more in thickness. Corallites 
comparatively small, of unequal size, irregularly distributed, their apertures rounded 
or subangular and more or less oblique; the largest nearly 1 mm. in diameter, the 
average adult size about 0.7 mm., while many are smaller, presumably younger, 
ranging in size between 0.2 and 0.5 mm. Septal strize apparently wanting. Here 
and there a faintly raised line may be detected on the inner side of the imperforate 
walls, but they are too irregular in their disposition and number to be called septa. 
*“ The majority of compound corals included in the Favositid@ are composed of polygonal prismatic cells or corallites in 
juxtaposition. When, however, these cells become free, their form is cylindrical. The polygonal form of closely arranged 
cells is therefore explained as the natural result of crowding”; Dr. O. E. Beecher, “Symmetrical cell development in the 
Favositide”’ (Trans. Connecticut Academy, vol. vili, p. 215, 1891), ‘ 
