188 Wisconsin Academy of Sciences, Arts, and Letters. 



the surface of some of the blocks oE shale, and though their di- 

 ameter is hardly larger than that of a knitting needle, their pecul- 

 iar sharp annulations distinguish them at a glance. The surface 

 pores are fine as needle points, yet under the microscope show in 

 general an elliptical section and are separated by grooved walls 

 giving to each opening a distinct margin or rim which is elevated 

 into a sharp spine on the lower side. The genus Fistidapora ex- 

 hibits a still further remove from the Bryozoan type. The larger 

 cells in this series have plainly marked transverse partitions as in 

 the Favosite corals. Still we have in some forms thin incrusting 

 layers and masses built up by the superposition of these layers. 

 Our collections contain several new species of this genus, two of 

 which have been described. The two forms to which I wish to 

 call your attention now are F. solidissima and i^. lens. The sur- 

 face markings in these species are nearly alike ; the former pre- 

 sents solid, cylindrical or flattened stems, often branching, while 

 the latter presents disk-like expansions with openings on one side 

 only. The surface of the former shows very small elliptical cells, 

 separated by comparatively thick walls or interspaces which are 

 studded by minute pores arranged in one, two, or sometimes three 

 rows between the cells. Twelve to sixteen of these larger cells 

 are found in the space of an eighth of an inch, measured along 

 the branches. Iq F. lens the cells are rather larger and the 

 interspaces narrower; otherwise the appearance of the surface in 

 these species is similar. 



The forms already noticed are generally considered to be Bryo- 

 zoans. The difference of opinion that has been referred to applies 

 principally to the remaining forms, and at this point, therefore, we 

 should look for some important fundamental distinctions. 



The genus Stellipora stands nearest to those just noted, and, 

 therefore, claims our attention. The beautiful form, S. poly- 

 stomella, is one of our mo^t common fossils: and although we ob- 

 tain only fragments of its broad frond like expansions, the 

 star-like tubercles that stud its surface, when perfectly preserved, 

 render it one of the most attractive species to the casual observer. 

 Our species is identified with the form described by Nicholson in 

 the Ohio reports, but presents some points of difference. This 



