PALEONTOLOGY. 467 



The examples observed vary considerable in form according to their 

 relative age, the smaller ones being shorter above than figured, with nar- 

 rower areas and shorter poral plates, while the diameter is somewhat less. 

 The species is proportionally broader and shorter than P. pyriformis Say- 

 although somewhat resembling it, but is sufficiently distinct to be readily 

 recognized. 



Formation and Locality. — In the Maxville limestone (Chester group), 

 at Xewtonville, Ohio. Collection of Columbia College. 



MOLLUSCOIDA. 



BRYOZOA. 



Genus POLYPORA McCoy. 

 Polypora Varsonviensisf 



fPolypora tarsouviensis Prout, Trans. St. Louis Acad. Nat. Sci., vol. i, p. 237, pi. 

 15, fig. 3. 



Some macerated fragments of Polypora, very closely resembling this 

 species, have been examined on the surface of thin shaly layers of the 

 Maxville limestones, from Newtonville, Ohio. But the examples are too 

 much worn and too fragmentary for description or illustration. A species 

 of FenesteLa has also been detected showing only the nonporiferous sur- 

 faces of fragments. The rays are very fine and slender, with slightly 

 elongated, quadrangular fenestrules. The rays are finely striate longitu- 

 dinally, but too imperfect for use or identification. 



Synocladia rectistyla. 



Plate IX, figs. 9 and 10. 



Svnocladia rectistyla Whitf., Ann. X. Y. Acad. Sci., 18S2, p. 220. 



Bryozoum growing in spreading funnel-formed fronds, rising from a rooted 

 base and widely diverging in their upward growth ; the inner surface of the cup 

 bearing pores. Rays straight and somewhat rigid in their upward direction, with 

 frequent bifurcations, which are not abrupt with rapidly diverging branches, but 

 rise gradually from a thickened space, and gradually diverge as slender but con- 

 stantly thickened rays until the normal strength is attained. 



The rays are slender, rather closely arranged ; about six of them occupying the 

 space of a fourth of an inch in the widest parts, and from eleven to twelve may be 

 counted in the same space in the most crowded parts. 



Transverse dissepiments nearly as strong as the longitudinal rays, and often 

 slightly arched upwards between them in the wider parts, but more frequently di- 

 rected obliquely upward in passing in one ray to the next and very often directed 

 upward to the right from one side of a ray, and to the left on the opposite 

 side; but they are generally direct in the more crowded portions. The middle 

 of the ray on the poriferous surface is elevated or roof-like, with a central crest or 

 ridge bearing distant nodes ; a single row of large pores is arranged on each side, 

 which are usually less than their own diameter apart, and more or less alternating 

 with those of the opposite side. From two to three pores occupy each side of each 

 fenestrule, and the pores are margined by an elevated lip, which on unworn spaces 



