BRYOZOA. 



rhombic or subpolygonal, with no marked regularity of arrange- 

 ment, seven or eight in three mm. There are groups of slightly 

 larger cell apertures which are arranged about small and scarcely 

 perceptible macula*. Walls of zooecia thin and with a peculiar 

 ragged structure. Lunaria inconspicuous, easily overlooked. 

 Mesopores few, generally only two or three at the center of the 

 clusters. They are without the lunarium and have thicker walls 

 than the zotecia. Diaphragms thin and somewhat more than 

 their own diameter apart. 



The external form, and the extreme paucity of the mesopores, 

 ilisting-uish this species from all the prescribed forms. It is more 

 closely approached by a large massive species that occurs rather 

 abundantly in a layer at the base of the Cincinnati group, 

 which is exposed near Harrodsburg, Ky. 



Position and locality: Cincinnati group; not uncommon at 

 Wilmington, 111. 



AXOLOTICHIA Clrich. 



(For generic diagnosis see page 381.) 



This genus is proposed for the reception of the following spe- 

 cies, and another that I have lately described from the Trenton 

 shales of Minnesota as Crepipora, impolita, (14th Ann. Rep. St. 

 Geol. Minn.). The tubulose structure of the lunarium is re- 

 garded as the principal distinctive character. The number of 

 these minute vertical tubes varies with the species, since in the 

 Minnesota form there are usually only three to each lunarium, 

 while in the Illinois species there are from five to seven. 



AXOLOTICHIA POXDEKOSA Ulrich. 



PL XTJ. fig. 3-Sd. 



Zoariuin forming large, irregular, massive branches. Surface 

 smooth. Apertures approximately direct, irregularly sub-circu- 

 lar or oval, eight or nine in three mm. Their arrangement is 

 rather irregular, and there are no clusters of large ones. Lu- 

 narial hood inconspicuous, with minute pores in the perfect 

 Mate. Zooecial tubes thin-walled throughout, yet considerably 



stronger near the surface than in the axial region, proceeding 

 59 



