426 PALEONTOLOGY OF ILLINOIS. 



Kinderhook group; L. gracillimum Ulr., in the Burlington and 

 Keokuk groups; L. punctatum Hall, and L. foliatum Ulr., in 

 the Keokuk group, and L.? araneum Ulr., in the Chester group. 

 Beside, several undescribed species are known, one from the 

 Hamilton, one from the Keokuk, one from the Chester, and 

 another from the Coal Measures. 



LEIOCLEMA WILMINGTONENSE Ulrich. 



PL XXXIV. flg. 4-46. 



Zoarium compressed, subramose; the type specimen is about 

 twenty-two mm. in width and about ten mm. in thickness, 

 surface smooth, unmarked by maculae, or monticules. Zooecial 

 tubes slightly inclined from the vertical in the center of the 

 branch, and reach the surface by a rather sharp curve; pro- 

 vided with a few diaphragms near the cortical region. Walls 

 but little thickened in the peripheral portion. Zooecia about 

 four to one mm. Apertures of zooecia circular, about 0.2 mm. 

 in diameter, seldom in contact, being nearly always completely 

 surrounded by angular mesopores, which are almost as large 

 as the zooecia. Diaphragms numerous in the mesopores, from 

 0.05 to 0.10 mm. distant from one another. Acanthopores 

 small and inconspicuous. 



Some care is required to distinguish this species from the some- 

 what similar Hoinotrypella contexts, which is associated with 

 it and, like it, has thin-walled zooecia separated by large meso- 

 pores. Sections at once prove the distinctness of the two forms, 

 the species here under consideration being entirely devoid of the 

 cystiphragms which are so abundant in H. context a. The 

 nearest congener of this species is the L. occidens Hall and 

 Whitfield. 



Position and locality: Cincinnati group, Wilmington, 111. 



LEIOCLEMA OCCIDENS Hall and Whitfield. 



Fistulipora occidens H. & W. 23 Beg. Eep. State Mus. N. Y., p. 228. PL V, flg.9, 10; 1875. 



Callopora cincinnatiensis Ulrich. Jour. Cin. Soc. Nat. Hist. Vol. I, p. 93, PL IV, 

 fig. 8-86, 1878; Ibid. Vol. V, p. 142; PL VI, flg. 18-18a, 1882. 



Zoarium exceedingly variable in form, commonly irregularly 

 ramose or lobate. Surface smooth, occasionally (in exception- 



