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, pi. 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 Kiver limestone at Pauquette Rapids, Canada." 



Collectors. E. O. Ulrich and C. Schuchert. 



LICHENARIA MINOR, n. 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 striae 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 Fameitiike 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. C. E. Beechcr, "Symmetrical cell development in the 

 Favosttidai" (Trans. Connecticut Academy, vol. vill, p. 215, 1891). 



